Re: [syzbot] [hams?] KASAN: slab-use-after-free Read in nr_add_node

Re: [syzbot] [hams?] KASAN: slab-use-after-free Read in nr_add_node

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in nr_add_node

==================================================================
BUG: KASAN: slab-use-after-free in nr_add_node+0x2b65/0x2bd0 net/netrom/nr_route.c:249
Read of size 4 at addr ffff8880265a73b0 by task syz.0.5221/17351

CPU: 0 UID: 0 PID: 17351 Comm: syz.0.5221 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 nr_add_node+0x2b65/0x2bd0 net/netrom/nr_route.c:249
 nr_rt_ioctl+0x11b7/0x29b0 net/netrom/nr_route.c:652
 nr_ioctl+0x19a/0x2d0 net/netrom/af_netrom.c:1254
 sock_do_ioctl+0x118/0x280 net/socket.c:1254
 sock_ioctl+0x227/0x6b0 net/socket.c:1375
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff9fdb8efc9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff9fe9f1038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ff9fdde5fa0 RCX: 00007ff9fdb8efc9
RDX: 0000200000000280 RSI: 000000000000890b RDI: 0000000000000004
RBP: 00007ff9fdc11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff9fdde6038 R14: 00007ff9fdde5fa0 R15: 00007ffd8e5d4ad8
 </TASK>

Allocated by task 17330:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 poison_kmalloc_redzone mm/kasan/common.c:400 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:417
 kmalloc_noprof include/linux/slab.h:957 [inline]
 nr_add_node+0xe4e/0x2bd0 net/netrom/nr_route.c:146
 nr_rt_ioctl+0x11b7/0x29b0 net/netrom/nr_route.c:652
 nr_ioctl+0x19a/0x2d0 net/netrom/af_netrom.c:1254
 sock_do_ioctl+0x118/0x280 net/socket.c:1254
 sock_ioctl+0x227/0x6b0 net/socket.c:1375
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 17351:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 __kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:587
 kasan_save_free_info mm/kasan/kasan.h:406 [inline]
 poison_slab_object mm/kasan/common.c:252 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:284
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2530 [inline]
 slab_free mm/slub.c:6619 [inline]
 kfree+0x2b8/0x6d0 mm/slub.c:6826
 nr_neigh_put include/net/netrom.h:143 [inline]
 nr_neigh_put include/net/netrom.h:137 [inline]
 nr_add_node+0x2389/0x2bd0 net/netrom/nr_route.c:247
 nr_rt_ioctl+0x11b7/0x29b0 net/netrom/nr_route.c:652
 nr_ioctl+0x19a/0x2d0 net/netrom/af_netrom.c:1254
 sock_do_ioctl+0x118/0x280 net/socket.c:1254
 sock_ioctl+0x227/0x6b0 net/socket.c:1375
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8880265a7380
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 48 bytes inside of
 freed 64-byte region [ffff8880265a7380, ffff8880265a73c0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x265a7
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801b4428c0 ffffea0000b7abc0 dead000000000004
raw: 0000000000000000 0000000000200020 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 132, tgid 132 (kworker/0:2), ts 9597767021, free_ts 8864964788
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1850
 prep_new_page mm/page_alloc.c:1858 [inline]
 get_page_from_freelist+0x10a3/0x3a30 mm/page_alloc.c:3884
 __alloc_frozen_pages_noprof+0x25f/0x2470 mm/page_alloc.c:5183
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:3046 [inline]
 allocate_slab mm/slub.c:3219 [inline]
 new_slab+0x24a/0x360 mm/slub.c:3273
 ___slab_alloc+0xdc4/0x1ae0 mm/slub.c:4643
 __slab_alloc.constprop.0+0x63/0x110 mm/slub.c:4762
 __slab_alloc_node mm/slub.c:4838 [inline]
 slab_alloc_node mm/slub.c:5260 [inline]
 __do_kmalloc_node mm/slub.c:5633 [inline]
 __kmalloc_noprof+0x501/0x880 mm/slub.c:5646
 kmalloc_noprof include/linux/slab.h:961 [inline]
 kmalloc_array_noprof include/linux/slab.h:1003 [inline]
 drm_atomic_state_init+0x17b/0x320 drivers/gpu/drm/drm_atomic.c:137
 drm_atomic_state_alloc drivers/gpu/drm/drm_atomic.c:176 [inline]
 drm_atomic_state_alloc+0xd3/0x120 drivers/gpu/drm/drm_atomic.c:166
 drm_atomic_helper_dirtyfb+0xc8/0x780 drivers/gpu/drm/drm_damage_helper.c:128
 drm_fbdev_shmem_helper_fb_dirty+0x1cc/0x340 drivers/gpu/drm/drm_fbdev_shmem.c:118
 drm_fb_helper_fb_dirty drivers/gpu/drm/drm_fb_helper.c:380 [inline]
 drm_fb_helper_damage_work+0x27e/0x5f0 drivers/gpu/drm/drm_fb_helper.c:403
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263
 process_scheduled_works kernel/workqueue.c:3346 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
 kthread+0x3c5/0x780 kernel/kthread.c:463
page last free pid 10 tgid 10 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1394 [inline]
 __free_frozen_pages+0x7df/0x1160 mm/page_alloc.c:2906
 vfree+0x1fd/0xb50 mm/vmalloc.c:3440
 delayed_vfree_work+0x56/0x70 mm/vmalloc.c:3359
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263
 process_scheduled_works kernel/workqueue.c:3346 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff8880265a7280: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8880265a7300: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
>ffff8880265a7380: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                                     ^
 ffff8880265a7400: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8880265a7480: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
==================================================================


Tested on:

commit:         1c64efcb Merge tag 'rust-rustfmt' of git://git.kernel...
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=135d0de2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f3e7b5a3627a90dd
dashboard link: https://syzkaller.appspot.com/bug?extid=2860e75836a08b172755
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=14bd03cd980000

Re: [syzbot] [hams?] KASAN: slab-use-after-free Read in nr_add_node

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in nr_add_node

==================================================================
BUG: KASAN: slab-use-after-free in nr_add_node+0x25e5/0x2c10 net/netrom/nr_route.c:249
Read of size 4 at addr ffff88802b876030 by task syz.2.1937/10375

CPU: 0 UID: 0 PID: 10375 Comm: syz.2.1937 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 nr_add_node+0x25e5/0x2c10 net/netrom/nr_route.c:249
 nr_rt_ioctl+0x11b7/0x29b0 net/netrom/nr_route.c:653
 nr_ioctl+0x19a/0x2d0 net/netrom/af_netrom.c:1254
 sock_do_ioctl+0x118/0x280 net/socket.c:1254
 sock_ioctl+0x227/0x6b0 net/socket.c:1375
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f35ebf8efc9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f35ecd77038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f35ec1e5fa0 RCX: 00007f35ebf8efc9
RDX: 0000200000000280 RSI: 000000000000890b RDI: 0000000000000004
RBP: 00007f35ec011f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f35ec1e6038 R14: 00007f35ec1e5fa0 R15: 00007ffff17dcae8
 </TASK>

Allocated by task 10366:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 poison_kmalloc_redzone mm/kasan/common.c:400 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:417
 kmalloc_noprof include/linux/slab.h:957 [inline]
 nr_add_node+0xe4e/0x2c10 net/netrom/nr_route.c:146
 nr_rt_ioctl+0x11b7/0x29b0 net/netrom/nr_route.c:653
 nr_ioctl+0x19a/0x2d0 net/netrom/af_netrom.c:1254
 sock_do_ioctl+0x118/0x280 net/socket.c:1254
 sock_ioctl+0x227/0x6b0 net/socket.c:1375
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88802b876000
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 48 bytes inside of
 freed 64-byte region [ffff88802b876000, ffff88802b876040)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2b876
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801b4428c0 ffffea0000926300 dead000000000006
raw: 0000000000000000 0000000000200020 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 6284, tgid 6284 (syz-executor), ts 96678923529, free_ts 96199339256
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1850
 prep_new_page mm/page_alloc.c:1858 [inline]
 get_page_from_freelist+0x10a3/0x3a30 mm/page_alloc.c:3884
 __alloc_frozen_pages_noprof+0x25f/0x2470 mm/page_alloc.c:5183
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:3046 [inline]
 allocate_slab mm/slub.c:3219 [inline]
 new_slab+0x24a/0x360 mm/slub.c:3273
 ___slab_alloc+0xdc4/0x1ae0 mm/slub.c:4643
 __slab_alloc.constprop.0+0x63/0x110 mm/slub.c:4762
 __slab_alloc_node mm/slub.c:4838 [inline]
 slab_alloc_node mm/slub.c:5260 [inline]
 __kmalloc_cache_noprof+0x477/0x780 mm/slub.c:5750
 kmalloc_noprof include/linux/slab.h:957 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 mpls_add_dev net/mpls/af_mpls.c:1443 [inline]
 mpls_dev_notify+0x346/0xa20 net/mpls/af_mpls.c:1600
 notifier_call_chain+0xbc/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2229
 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
 call_netdevice_notifiers net/core/dev.c:2281 [inline]
 register_netdevice+0x182e/0x2270 net/core/dev.c:11332
 nsim_init_netdevsim drivers/net/netdevsim/netdev.c:1059 [inline]
 nsim_create+0xdd5/0x1260 drivers/net/netdevsim/netdev.c:1141
 __nsim_dev_port_add+0x435/0x7d0 drivers/net/netdevsim/dev.c:1438
 nsim_dev_port_add_all drivers/net/netdevsim/dev.c:1494 [inline]
 nsim_drv_probe+0xe40/0x1520 drivers/net/netdevsim/dev.c:1653
 call_driver_probe drivers/base/dd.c:581 [inline]
 really_probe+0x241/0xa90 drivers/base/dd.c:659
page last free pid 6298 tgid 6298 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1394 [inline]
 __free_frozen_pages+0x7df/0x1160 mm/page_alloc.c:2906
 discard_slab mm/slub.c:3317 [inline]
 __put_partials+0x130/0x170 mm/slub.c:3864
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x4d/0x120 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:352
 kasan_slab_alloc include/linux/kasan.h:252 [inline]
 slab_post_alloc_hook mm/slub.c:4962 [inline]
 slab_alloc_node mm/slub.c:5272 [inline]
 kmem_cache_alloc_noprof+0x250/0x6e0 mm/slub.c:5279
 getname_flags.part.0+0x4c/0x550 fs/namei.c:146
 getname_flags+0x93/0xf0 include/linux/audit.h:345
 getname include/linux/fs.h:2922 [inline]
 getname_maybe_null include/linux/fs.h:2929 [inline]
 getname_maybe_null include/linux/fs.h:2926 [inline]
 vfs_fstatat+0xe1/0xf0 fs/stat.c:370
 __do_sys_newfstatat+0x97/0x120 fs/stat.c:542
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88802b875f00: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
 ffff88802b875f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802b876000: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                                     ^
 ffff88802b876080: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
 ffff88802b876100: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================


Tested on:

commit:         1c64efcb Merge tag 'rust-rustfmt' of git://git.kernel...
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1166f67c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f3e7b5a3627a90dd
dashboard link: https://syzkaller.appspot.com/bug?extid=2860e75836a08b172755
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1069dc58580000

Re: [syzbot] [hams?] KASAN: slab-use-after-free Read in nr_add_node

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in nr_add_node

==================================================================
BUG: KASAN: slab-use-after-free in nr_add_node+0x25e5/0x2c10 net/netrom/nr_route.c:249
Read of size 4 at addr ffff88805466ddb0 by task syz.1.4225/15237

CPU: 2 UID: 0 PID: 15237 Comm: syz.1.4225 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 nr_add_node+0x25e5/0x2c10 net/netrom/nr_route.c:249
 nr_rt_ioctl+0x11b7/0x29b0 net/netrom/nr_route.c:653
 nr_ioctl+0x19a/0x2d0 net/netrom/af_netrom.c:1254
 sock_do_ioctl+0x118/0x280 net/socket.c:1254
 sock_ioctl+0x227/0x6b0 net/socket.c:1375
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4229d8efc9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f422ac41038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f4229fe5fa0 RCX: 00007f4229d8efc9
RDX: 0000200000000280 RSI: 000000000000890b RDI: 0000000000000004
RBP: 00007f4229e11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4229fe6038 R14: 00007f4229fe5fa0 R15: 00007ffe9d4efb98
 </TASK>

Allocated by task 15224:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 poison_kmalloc_redzone mm/kasan/common.c:400 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:417
 kmalloc_noprof include/linux/slab.h:957 [inline]
 nr_add_node+0xe4e/0x2c10 net/netrom/nr_route.c:146
 nr_rt_ioctl+0x11b7/0x29b0 net/netrom/nr_route.c:653
 nr_ioctl+0x19a/0x2d0 net/netrom/af_netrom.c:1254
 sock_do_ioctl+0x118/0x280 net/socket.c:1254
 sock_ioctl+0x227/0x6b0 net/socket.c:1375
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 15237:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 __kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:587
 kasan_save_free_info mm/kasan/kasan.h:406 [inline]
 poison_slab_object mm/kasan/common.c:252 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:284
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2530 [inline]
 slab_free mm/slub.c:6619 [inline]
 kfree+0x2b8/0x6d0 mm/slub.c:6826
 nr_neigh_put include/net/netrom.h:143 [inline]
 nr_neigh_put include/net/netrom.h:137 [inline]
 nr_add_node+0x23c3/0x2c10 net/netrom/nr_route.c:246
 nr_rt_ioctl+0x11b7/0x29b0 net/netrom/nr_route.c:653
 nr_ioctl+0x19a/0x2d0 net/netrom/af_netrom.c:1254
 sock_do_ioctl+0x118/0x280 net/socket.c:1254
 sock_ioctl+0x227/0x6b0 net/socket.c:1375
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88805466dd80
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 48 bytes inside of
 freed 64-byte region [ffff88805466dd80, ffff88805466ddc0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5466d
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801b4428c0 ffffea0000867b00 dead000000000004
raw: 0000000000000000 0000000000200020 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5345, tgid 5345 (udevd), ts 58557594470, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1850
 prep_new_page mm/page_alloc.c:1858 [inline]
 get_page_from_freelist+0x10a3/0x3a30 mm/page_alloc.c:3884
 __alloc_frozen_pages_noprof+0x25f/0x2470 mm/page_alloc.c:5183
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:3046 [inline]
 allocate_slab mm/slub.c:3219 [inline]
 new_slab+0x24a/0x360 mm/slub.c:3273
 ___slab_alloc+0xdc4/0x1ae0 mm/slub.c:4643
 __slab_alloc.constprop.0+0x63/0x110 mm/slub.c:4762
 __slab_alloc_node mm/slub.c:4838 [inline]
 slab_alloc_node mm/slub.c:5260 [inline]
 __do_kmalloc_node mm/slub.c:5633 [inline]
 __kmalloc_noprof+0x501/0x880 mm/slub.c:5646
 kmalloc_noprof include/linux/slab.h:961 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 tomoyo_encode2+0x100/0x3e0 security/tomoyo/realpath.c:45
 tomoyo_encode+0x29/0x50 security/tomoyo/realpath.c:80
 tomoyo_realpath_from_path+0x18f/0x6e0 security/tomoyo/realpath.c:283
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_check_open_permission+0x2ab/0x3c0 security/tomoyo/file.c:771
 tomoyo_file_open+0x6b/0x90 security/tomoyo/tomoyo.c:334
 security_file_open+0x84/0x1e0 security/security.c:3183
 do_dentry_open+0x596/0x1530 fs/open.c:942
 vfs_open+0x82/0x3f0 fs/open.c:1097
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88805466dc80: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
 ffff88805466dd00: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
>ffff88805466dd80: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                                     ^
 ffff88805466de00: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
 ffff88805466de80: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
==================================================================


Tested on:

commit:         1c64efcb Merge tag 'rust-rustfmt' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12a8bde2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f3e7b5a3627a90dd
dashboard link: https://syzkaller.appspot.com/bug?extid=2860e75836a08b172755
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=13e20de2580000

Re: [syzbot] [hams?] KASAN: slab-use-after-free Read in nr_add_node

[syzbot]

> On 18.10.2025 13:37, syzbot wrote:
>> syzbot has found a reproducer for the following issue on:
>> 
>> HEAD commit:    f406055cb18c Merge tag 'arm64-fixes' of git://git.kernel.o..
>> git tree:       upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=11cf767c580000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=f3e7b5a3627a90dd
>> dashboard link: https://syzkaller.appspot.com/bug?extid=2860e75836a08b172755
>> compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=155f1de2580000
>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12b6b52f980000
>> 
>> Downloadable assets:
>> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-f406055c.raw.xz
>> vmlinux: https://storage.googleapis.com/syzbot-assets/a4db2a99bfb1/vmlinux-f406055c.xz
>> kernel image: https://storage.googleapis.com/syzbot-assets/91d1ca420bac/bzImage-f406055c.xz
>> 
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+2860e75836a08b172755@syzkaller.appspotmail.com
>> 
>> ==================================================================
>> BUG: KASAN: slab-use-after-free in nr_add_node+0x25db/0x2c00 net/netrom/nr_route.c:248
>> Read of size 4 at addr ffff888054b8cc30 by task syz.3.7839/22393
>
> #syz test linux-next

want either no args or 2 args (repo, branch), got 1

>
> diff --git a/net/netrom/nr_route.c b/net/netrom/nr_route.c
> index b94cb2ffbaf8..5fa7d9febbbb 100644
> --- a/net/netrom/nr_route.c
> +++ b/net/netrom/nr_route.c
> @@ -245,7 +245,9 @@ static int __must_check nr_add_node(ax25_address *nr, const char *mnemonic,
>  				nr_node->routes[2].neighbour->count--;
>  				nr_neigh_put(nr_node->routes[2].neighbour);
>  
> -				if (nr_node->routes[2].neighbour->count == 0 && !nr_node->routes[2].neighbour->locked)
> +				if (nr_node->routes[2].neighbour &&
> +				    nr_node->routes[2].neighbour->count == 0 &&
> +				    !nr_node->routes[2].neighbour->locked)
>  					nr_remove_neigh(nr_node->routes[2].neighbour);
>  
>  				nr_node->routes[2].quality   = quality;
>
> -- 
> Regards,
> listout

Re: [syzbot] [hams?] KASAN: slab-use-after-free Read in nr_add_node

[Brahmajit Das]

On 18.10.2025 13:37, syzbot wrote:
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    f406055cb18c Merge tag 'arm64-fixes' of git://git.kernel.o..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11cf767c580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=f3e7b5a3627a90dd
> dashboard link: https://syzkaller.appspot.com/bug?extid=2860e75836a08b172755
> compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=155f1de2580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12b6b52f980000
> 
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-f406055c.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/a4db2a99bfb1/vmlinux-f406055c.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/91d1ca420bac/bzImage-f406055c.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+2860e75836a08b172755@syzkaller.appspotmail.com
> 
> ==================================================================
> BUG: KASAN: slab-use-after-free in nr_add_node+0x25db/0x2c00 net/netrom/nr_route.c:248
> Read of size 4 at addr ffff888054b8cc30 by task syz.3.7839/22393

#syz test linux-next

diff --git a/net/netrom/nr_route.c b/net/netrom/nr_route.c
index b94cb2ffbaf8..5fa7d9febbbb 100644
--- a/net/netrom/nr_route.c
+++ b/net/netrom/nr_route.c
@@ -245,7 +245,9 @@ static int __must_check nr_add_node(ax25_address *nr, const char *mnemonic,
 				nr_node->routes[2].neighbour->count--;
 				nr_neigh_put(nr_node->routes[2].neighbour);
 
-				if (nr_node->routes[2].neighbour->count == 0 && !nr_node->routes[2].neighbour->locked)
+				if (nr_node->routes[2].neighbour &&
+				    nr_node->routes[2].neighbour->count == 0 &&
+				    !nr_node->routes[2].neighbour->locked)
 					nr_remove_neigh(nr_node->routes[2].neighbour);
 
 				nr_node->routes[2].quality   = quality;

-- 
Regards,
listout

Re: [syzbot] [hams?] KASAN: slab-use-after-free Read in nr_add_node

[Brahmajit Das]

On 18.10.2025 13:37, syzbot wrote:
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    f406055cb18c Merge tag 'arm64-fixes' of git://git.kernel.o..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11cf767c580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=f3e7b5a3627a90dd
> dashboard link: https://syzkaller.appspot.com/bug?extid=2860e75836a08b172755
> compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=155f1de2580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12b6b52f980000
> 
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-f406055c.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/a4db2a99bfb1/vmlinux-f406055c.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/91d1ca420bac/bzImage-f406055c.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+2860e75836a08b172755@syzkaller.appspotmail.com
> 
> ==================================================================
> BUG: KASAN: slab-use-after-free in nr_add_node+0x25db/0x2c00 net/netrom/nr_route.c:248
> Read of size 4 at addr ffff888054b8cc30 by task syz.3.7839/22393
> 

#syz test

diff --git a/net/netrom/nr_route.c b/net/netrom/nr_route.c
index b94cb2ffbaf8..5fa7d9febbbb 100644
--- a/net/netrom/nr_route.c
+++ b/net/netrom/nr_route.c
@@ -245,7 +245,9 @@ static int __must_check nr_add_node(ax25_address *nr, const char *mnemonic,
 				nr_node->routes[2].neighbour->count--;
 				nr_neigh_put(nr_node->routes[2].neighbour);
 
-				if (nr_node->routes[2].neighbour->count == 0 && !nr_node->routes[2].neighbour->locked)
+				if (nr_node->routes[2].neighbour &&
+				    nr_node->routes[2].neighbour->count == 0 &&
+				    !nr_node->routes[2].neighbour->locked)
 					nr_remove_neigh(nr_node->routes[2].neighbour);
 
 				nr_node->routes[2].quality   = quality;

-- 
Regards,
listout

Re: [syzbot] [hams?] KASAN: slab-use-after-free Read in nr_add_node

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    f406055cb18c Merge tag 'arm64-fixes' of git://git.kernel.o..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11cf767c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f3e7b5a3627a90dd
dashboard link: https://syzkaller.appspot.com/bug?extid=2860e75836a08b172755
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=155f1de2580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12b6b52f980000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-f406055c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a4db2a99bfb1/vmlinux-f406055c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/91d1ca420bac/bzImage-f406055c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2860e75836a08b172755@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in nr_add_node+0x25db/0x2c00 net/netrom/nr_route.c:248
Read of size 4 at addr ffff888054b8cc30 by task syz.3.7839/22393

CPU: 3 UID: 0 PID: 22393 Comm: syz.3.7839 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 nr_add_node+0x25db/0x2c00 net/netrom/nr_route.c:248
 nr_rt_ioctl+0x11b7/0x29b0 net/netrom/nr_route.c:651
 nr_ioctl+0x19a/0x2d0 net/netrom/af_netrom.c:1254
 sock_do_ioctl+0x118/0x280 net/socket.c:1254
 sock_ioctl+0x227/0x6b0 net/socket.c:1375
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7f4fb8efc9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7f509c5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f7f4fde5fa0 RCX: 00007f7f4fb8efc9
RDX: 0000200000000280 RSI: 000000000000890b RDI: 0000000000000004
RBP: 00007f7f4fc11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7f4fde6038 R14: 00007f7f4fde5fa0 R15: 00007ffd1bd56f18
 </TASK>

Allocated by task 22380:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 poison_kmalloc_redzone mm/kasan/common.c:400 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:417
 kmalloc_noprof include/linux/slab.h:957 [inline]
 nr_add_node+0xe4e/0x2c00 net/netrom/nr_route.c:146
 nr_rt_ioctl+0x11b7/0x29b0 net/netrom/nr_route.c:651
 nr_ioctl+0x19a/0x2d0 net/netrom/af_netrom.c:1254
 sock_do_ioctl+0x118/0x280 net/socket.c:1254
 sock_ioctl+0x227/0x6b0 net/socket.c:1375
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 22393:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 __kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:587
 kasan_save_free_info mm/kasan/kasan.h:406 [inline]
 poison_slab_object mm/kasan/common.c:252 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:284
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2523 [inline]
 slab_free mm/slub.c:6611 [inline]
 kfree+0x2b8/0x6d0 mm/slub.c:6818
 nr_neigh_put include/net/netrom.h:143 [inline]
 nr_neigh_put include/net/netrom.h:137 [inline]
 nr_add_node+0x23b9/0x2c00 net/netrom/nr_route.c:246
 nr_rt_ioctl+0x11b7/0x29b0 net/netrom/nr_route.c:651
 nr_ioctl+0x19a/0x2d0 net/netrom/af_netrom.c:1254
 sock_do_ioctl+0x118/0x280 net/socket.c:1254
 sock_ioctl+0x227/0x6b0 net/socket.c:1375
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888054b8cc00
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 48 bytes inside of
 freed 64-byte region [ffff888054b8cc00, ffff888054b8cc40)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x54b8c
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801b4428c0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000200020 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 6074, tgid 6074 (syz-executor), ts 126099390276, free_ts 126098882568
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1850
 prep_new_page mm/page_alloc.c:1858 [inline]
 get_page_from_freelist+0x10a3/0x3a30 mm/page_alloc.c:3884
 __alloc_frozen_pages_noprof+0x25f/0x2470 mm/page_alloc.c:5183
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:3039 [inline]
 allocate_slab mm/slub.c:3212 [inline]
 new_slab+0x24a/0x360 mm/slub.c:3266
 ___slab_alloc+0xdc4/0x1ae0 mm/slub.c:4636
 __slab_alloc.constprop.0+0x63/0x110 mm/slub.c:4755
 __slab_alloc_node mm/slub.c:4831 [inline]
 slab_alloc_node mm/slub.c:5253 [inline]
 __kmalloc_cache_noprof+0x477/0x780 mm/slub.c:5743
 kmalloc_noprof include/linux/slab.h:957 [inline]
 __team_option_inst_add+0xbf/0x330 drivers/net/team/team_core.c:160
 __team_option_inst_add_option drivers/net/team/team_core.c:182 [inline]
 __team_options_register+0x355/0x720 drivers/net/team/team_core.c:276
 team_options_register drivers/net/team/team_core.c:341 [inline]
 team_init+0x5c8/0xce0 drivers/net/team/team_core.c:1658
 register_netdevice+0x653/0x2270 net/core/dev.c:11221
 team_newlink+0xb4/0x190 drivers/net/team/team_core.c:2213
 rtnl_newlink_create net/core/rtnetlink.c:3833 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3950 [inline]
 rtnl_newlink+0xc45/0x2000 net/core/rtnetlink.c:4065
 rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:6954
 netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2552
page last free pid 6074 tgid 6074 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1394 [inline]
 __free_frozen_pages+0x7df/0x1160 mm/page_alloc.c:2906
 selinux_genfs_get_sid security/selinux/hooks.c:1357 [inline]
 inode_doinit_with_dentry+0xacb/0x12e0 security/selinux/hooks.c:1555
 selinux_d_instantiate+0x26/0x30 security/selinux/hooks.c:6523
 security_d_instantiate+0x142/0x1a0 security/security.c:4148
 d_instantiate+0x5c/0x90 fs/dcache.c:1961
 __debugfs_create_file+0x286/0x6b0 fs/debugfs/inode.c:459
 debugfs_create_file_full+0x41/0x60 fs/debugfs/inode.c:469
 ref_tracker_dir_debugfs+0x19d/0x290 lib/ref_tracker.c:441
 ref_tracker_dir_init include/linux/ref_tracker.h:70 [inline]
 alloc_netdev_mqs+0x314/0x1550 net/core/dev.c:11907
 rtnl_create_link+0xc08/0xf90 net/core/rtnetlink.c:3641
 rtnl_newlink_create net/core/rtnetlink.c:3823 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3950 [inline]
 rtnl_newlink+0xb69/0x2000 net/core/rtnetlink.c:4065
 rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:6954
 netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2552
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 __sys_sendto+0x4a3/0x520 net/socket.c:2244

Memory state around the buggy address:
 ffff888054b8cb00: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
 ffff888054b8cb80: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888054b8cc00: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                                     ^
 ffff888054b8cc80: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
 ffff888054b8cd00: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
==================================================================


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

[syzbot] [hams?] KASAN: slab-use-after-free Read in nr_add_node

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    846bd2225ec3 Add linux-next specific files for 20250919
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=130c08e2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=135377594f35b576
dashboard link: https://syzkaller.appspot.com/bug?extid=2860e75836a08b172755
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13f3fe42580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c53d48022f8a/disk-846bd222.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/483534e784c8/vmlinux-846bd222.xz
kernel image: https://storage.googleapis.com/syzbot-assets/721b36eec9b3/bzImage-846bd222.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2860e75836a08b172755@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in nr_add_node+0x251b/0x2580 net/netrom/nr_route.c:248
Read of size 2 at addr ffff888078ae2632 by task syz.0.4719/15936

CPU: 0 UID: 0 PID: 15936 Comm: syz.0.4719 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 nr_add_node+0x251b/0x2580 net/netrom/nr_route.c:248
 nr_rt_ioctl+0x9f1/0xb00 net/netrom/nr_route.c:651
 sock_do_ioctl+0xdc/0x300 net/socket.c:1241
 sock_ioctl+0x576/0x790 net/socket.c:1362
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f29de38ec29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f29df216038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f29de5d5fa0 RCX: 00007f29de38ec29
RDX: 0000200000000000 RSI: 000000000000890b RDI: 0000000000000004
RBP: 00007f29de411e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f29de5d6038 R14: 00007f29de5d5fa0 R15: 00007ffedaf2ceb8
 </TASK>

Allocated by task 15939:
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 poison_kmalloc_redzone mm/kasan/common.c:400 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:417
 kasan_kmalloc include/linux/kasan.h:262 [inline]
 __kmalloc_cache_noprof+0x3d5/0x6f0 mm/slub.c:5723
 kmalloc_noprof include/linux/slab.h:957 [inline]
 nr_add_node+0x804/0x2580 net/netrom/nr_route.c:146
 nr_rt_ioctl+0x9f1/0xb00 net/netrom/nr_route.c:651
 sock_do_ioctl+0xdc/0x300 net/socket.c:1241
 sock_ioctl+0x576/0x790 net/socket.c:1362
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 15936:
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 __kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587
 kasan_save_free_info mm/kasan/kasan.h:406 [inline]
 poison_slab_object mm/kasan/common.c:252 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2507 [inline]
 slab_free mm/slub.c:6557 [inline]
 kfree+0x19a/0x6d0 mm/slub.c:6765
 nr_add_node+0x1cbe/0x2580 net/netrom/nr_route.c:246
 nr_rt_ioctl+0x9f1/0xb00 net/netrom/nr_route.c:651
 sock_do_ioctl+0xdc/0x300 net/socket.c:1241
 sock_ioctl+0x576/0x790 net/socket.c:1362
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888078ae2600
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 50 bytes inside of
 freed 64-byte region [ffff888078ae2600, ffff888078ae2640)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x78ae2
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801b0418c0 ffffea0000c51900 dead000000000004
raw: 0000000000000000 0000000000200020 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5233, tgid 5233 (udevd), ts 92365645188, free_ts 92323224662
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1850
 prep_new_page mm/page_alloc.c:1858 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3869
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5159
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:3023 [inline]
 allocate_slab+0x96/0x3a0 mm/slub.c:3196
 new_slab mm/slub.c:3250 [inline]
 ___slab_alloc+0xe94/0x1920 mm/slub.c:4626
 __slab_alloc+0x65/0x100 mm/slub.c:4745
 __slab_alloc_node mm/slub.c:4821 [inline]
 slab_alloc_node mm/slub.c:5232 [inline]
 __do_kmalloc_node mm/slub.c:5601 [inline]
 __kmalloc_noprof+0x471/0x7f0 mm/slub.c:5614
 kmalloc_noprof include/linux/slab.h:961 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 tomoyo_encode2 security/tomoyo/realpath.c:45 [inline]
 tomoyo_encode+0x28b/0x550 security/tomoyo/realpath.c:80
 tomoyo_realpath_from_path+0x58d/0x5d0 security/tomoyo/realpath.c:283
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x213/0x4b0 security/tomoyo/file.c:822
 security_inode_getattr+0x12f/0x330 security/security.c:2416
 vfs_getattr fs/stat.c:259 [inline]
 vfs_fstat fs/stat.c:281 [inline]
 __do_sys_newfstat fs/stat.c:555 [inline]
 __se_sys_newfstat fs/stat.c:550 [inline]
 __x64_sys_newfstat+0xfc/0x200 fs/stat.c:550
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5528 tgid 5528 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1394 [inline]
 __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2906
 rcu_do_batch kernel/rcu/tree.c:2605 [inline]
 rcu_core+0xcab/0x1770 kernel/rcu/tree.c:2861
 handle_softirqs+0x286/0x870 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:723
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697

Memory state around the buggy address:
 ffff888078ae2500: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888078ae2580: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888078ae2600: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                                     ^
 ffff888078ae2680: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888078ae2700: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================


---
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If the report is already addressed, let syzbot know by replying with:
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If you want syzbot to run the reproducer, reply with:
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