[syzbot] [nvme?] KASAN: slab-use-after-free Read in nvmet_port_subsys_allow_link

[syzbot] [nvme?] KASAN: slab-use-after-free Read in nvmet_port_subsys_allow_link

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    26260251022f Merge tag 'livepatching-for-7.3' of git://git..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10519179580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b5a17c415a27e42e
dashboard link: https://syzkaller.appspot.com/bug?extid=b0996ac2197dd7420c3e
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/05f9f33a1f1f/disk-26260251.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/197f5b9a6961/vmlinux-26260251.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ad671f043000/bzImage-26260251.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b0996ac2197dd7420c3e@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in nvmet_port_subsys_allow_link+0x41/0x2e0 drivers/nvme/target/configfs.c:1059
Read of size 8 at addr ffff88801af304c8 by task syz.2.79/6124

CPU: 1 UID: 0 PID: 6124 Comm: syz.2.79 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 nvmet_port_subsys_allow_link+0x41/0x2e0 drivers/nvme/target/configfs.c:1059
 configfs_symlink+0x59a/0x1030 fs/configfs/symlink.c:196
 vfs_symlink+0x18b/0x330 fs/namei.c:5794
 filename_symlinkat+0x1cd/0x420 fs/namei.c:5819
 __do_sys_symlinkat fs/namei.c:5839 [inline]
 __se_sys_symlinkat+0x4e/0x2b0 fs/namei.c:5834
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcbe476e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fcbe29c6028 EFLAGS: 00000246 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 00007fcbe49f5fa0 RCX: 00007fcbe476e0d9
RDX: 0000200000000600 RSI: ffffffffffffff9c RDI: 00002000000005c0
RBP: 00007fcbe4805024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcbe49f6038 R14: 00007fcbe49f5fa0 R15: 00007fffa285bf38
 </TASK>

Allocated by task 6060:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x3da/0x6b0 mm/slub.c:5484
 _kmalloc_noprof include/linux/slab.h:988 [inline]
 _kzalloc_noprof include/linux/slab.h:1309 [inline]
 nvmet_ports_make+0xe6/0xf00 drivers/nvme/target/configfs.c:2051
 configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1360
 vfs_mkdir+0x408/0x620 fs/namei.c:5410
 filename_mkdirat+0x289/0x520 fs/namei.c:5443
 __do_sys_mkdirat fs/namei.c:5464 [inline]
 __se_sys_mkdirat+0x35/0x150 fs/namei.c:5461
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 6127:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2678 [inline]
 slab_free mm/slub.c:6372 [inline]
 kfree+0x1c5/0x6d0 mm/slub.c:6687
 config_item_cleanup fs/configfs/item.c:128 [inline]
 config_item_release+0x13a/0x2d0 fs/configfs/item.c:137
 configfs_rmdir+0x885/0x950 fs/configfs/dir.c:1571
 vfs_rmdir+0x3e9/0x6b0 fs/namei.c:5515
 filename_rmdir+0x292/0x520 fs/namei.c:5572
 __do_sys_unlinkat fs/namei.c:5747 [inline]
 __se_sys_unlinkat+0x71/0x1a0 fs/namei.c:5740
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88801af30000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 1224 bytes inside of
 freed 4096-byte region [ffff88801af30000, ffff88801af31000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1af30
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x80000000000040(head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000040 ffff88813ffbc140 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800040004 00000000f5000000 0000000000000000
head: 0080000000000040 ffff88813ffbc140 dead000000000100 dead000000000122
head: 0000000000000000 0000000800040004 00000000f5000000 0000000000000000
head: 0080000000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5585, tgid 5585 (syz-executor), ts 106684716313
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1871
 prep_new_page mm/page_alloc.c:1879 [inline]
 get_page_from_freelist+0x2591/0x2600 mm/page_alloc.c:3943
 __alloc_frozen_pages_noprof+0x230/0x5c0 mm/page_alloc.c:5436
 alloc_slab_page mm/slub.c:3267 [inline]
 allocate_slab+0x7c/0x5e0 mm/slub.c:3382
 new_slab mm/slub.c:3428 [inline]
 refill_objects+0x2d8/0x350 mm/slub.c:7305
 refill_sheaf mm/slub.c:2805 [inline]
 __pcs_replace_empty_main+0x334/0x690 mm/slub.c:4677
 alloc_from_pcs mm/slub.c:4775 [inline]
 slab_alloc_node mm/slub.c:4907 [inline]
 __do_kmalloc_node mm/slub.c:5336 [inline]
 __kmalloc_noprof+0x54c/0x780 mm/slub.c:5362
 _kmalloc_noprof include/linux/slab.h:992 [inline]
 tomoyo_realpath_from_path+0xef/0x640 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x283/0x560 security/tomoyo/file.c:827
 security_inode_getattr+0x12b/0x310 security/security.c:1895
 vfs_getattr+0x23/0x70 fs/stat.c:259
 vfs_statx_path+0x2b/0x230 fs/stat.c:299
 vfs_statx+0x12e/0x200 fs/stat.c:356
 vfs_fstatat+0x11b/0x170 fs/stat.c:373
 __do_sys_newfstatat fs/stat.c:538 [inline]
 __se_sys_newfstatat fs/stat.c:532 [inline]
 __x64_sys_newfstatat+0x151/0x200 fs/stat.c:532
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
page last free pid 5783 tgid 5783 ts 106512362313 stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 __free_pages_prepare mm/page_alloc.c:1418 [inline]
 __free_frozen_pages+0xf8e/0x1070 mm/page_alloc.c:2962
 __slab_free+0x252/0x2a0 mm/slub.c:5736
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4586 [inline]
 slab_alloc_node mm/slub.c:4919 [inline]
 kmem_cache_alloc_noprof+0x35d/0x660 mm/slub.c:4933
 alloc_filename fs/namei.c:147 [inline]
 do_getname+0x2e/0x250 fs/namei.c:187
 class_filename_flags_constructor include/linux/fs.h:2587 [inline]
 do_sys_openat2+0xcc/0x200 fs/open.c:1416
 do_sys_open fs/open.c:1423 [inline]
 __do_sys_openat fs/open.c:1439 [inline]
 __se_sys_openat fs/open.c:1434 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1434
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88801af30380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801af30400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88801af30480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff88801af30500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801af30580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

Re: [syzbot] [nvme?] KASAN: slab-use-after-free Read in nvmet_port_subsys_allow_link

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    818bebeb63dd drm/xe: Don't hand out the flat CCS storage a..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1458e579580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ccca94d2c01b9e78
dashboard link: https://syzkaller.appspot.com/bug?extid=b0996ac2197dd7420c3e
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11ab6d49580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b0996ac2197dd7420c3e@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000022: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000110-0x0000000000000117]
CPU: 2 UID: 0 PID: 6022 Comm: syz-executor823 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:nvmet_port_subsys_allow_link+0x108/0x390 drivers/nvme/target/configfs.c:1076
Code: 00 00 4d 89 66 10 48 c7 c7 e0 d9 f3 8f 4d 8d af 10 01 00 00 e8 29 aa 1f 05 4c 89 ea 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 f0 01 00 00 49 8b 9f 10 01 00 00 4c 39 eb 0f 84
RSP: 0018:ffffc9000283fc88 EFLAGS: 00010206

RAX: dffffc0000000000 RBX: ffff8880271f8498 RCX: 0000000000000000
RDX: 0000000000000022 RSI: 0000000000000008 RDI: 0000000000000001
RBP: ffffffff8ff44260 R08: 0000000000000001 R09: fffffbfff1fe7b3d
R10: ffffffff8ff3d9ef R11: 0000000000000000 R12: ffff88802c543000
R13: 0000000000000110 R14: ffff88803dc39b80 R15: 0000000000000000
FS:  00007f53b85796c0(0000) GS:ffff8880d5da2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f53b5572ff8 CR3: 0000000055990000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 configfs_symlink+0x540/0x11f0 fs/configfs/symlink.c:196
 vfs_symlink fs/namei.c:5794 [inline]
 vfs_symlink+0x178/0x4d0 fs/namei.c:5773
 filename_symlinkat+0x2a6/0x560 fs/namei.c:5819
 __do_sys_symlinkat fs/namei.c:5839 [inline]
 __se_sys_symlinkat fs/namei.c:5834 [inline]
 __x64_sys_symlinkat+0x9c/0xe0 fs/namei.c:5834
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f53b85ae459
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 0f 1f 44 00 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 d0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f53b85791f8 EFLAGS: 00000246
 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 00007f53b861b028 RCX: 00007f53b85ae459
RDX: 00007f53b861b028 RSI: 00000000ffffff9c RDI: 00007f53b861b060
RBP: 00007f53b861b060 R08: 00007f53b85796c0 R09: 00007f53b85796c0
R10: 00007f53b85796c0 R11: 0000000000000246 R12: ffffffffffffffd0
R13: 0000000000000010 R14: 00007ffff5cb1e50 R15: 00007ffff5cb1f38
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:nvmet_port_subsys_allow_link+0x108/0x390 drivers/nvme/target/configfs.c:1076
Code: 00 00 4d 89 66 10 48 c7 c7 e0 d9 f3 8f 4d 8d af 10 01 00 00 e8 29 aa 1f 05 4c 89 ea 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 f0 01 00 00 49 8b 9f 10 01 00 00 4c 39 eb 0f 84
RSP: 0018:ffffc9000283fc88 EFLAGS: 00010206

RAX: dffffc0000000000 RBX: ffff8880271f8498 RCX: 0000000000000000
RDX: 0000000000000022 RSI: 0000000000000008 RDI: 0000000000000001
RBP: ffffffff8ff44260 R08: 0000000000000001 R09: fffffbfff1fe7b3d
R10: ffffffff8ff3d9ef R11: 0000000000000000 R12: ffff88802c543000
R13: 0000000000000110 R14: ffff88803dc39b80 R15: 0000000000000000
FS:  00007f53b85796c0(0000) GS:ffff8880d5da2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f53b5572ff8 CR3: 0000000055990000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	4d 89 66 10          	mov    %r12,0x10(%r14)
   6:	48 c7 c7 e0 d9 f3 8f 	mov    $0xffffffff8ff3d9e0,%rdi
   d:	4d 8d af 10 01 00 00 	lea    0x110(%r15),%r13
  14:	e8 29 aa 1f 05       	call   0x51faa42
  19:	4c 89 ea             	mov    %r13,%rdx
  1c:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  23:	fc ff df
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2e:	0f 85 f0 01 00 00    	jne    0x224
  34:	49 8b 9f 10 01 00 00 	mov    0x110(%r15),%rbx
  3b:	4c 39 eb             	cmp    %r13,%rbx
  3e:	0f                   	.byte 0xf
  3f:	84                   	.byte 0x84


---
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.