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List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6e02:3499:b0:433:31a0:4e6d with SMTP id e9e14a558f8ab-43331a051b6mr8578255ab.10.1762127310115; Sun, 02 Nov 2025 15:48:30 -0800 (PST) Date: Sun, 02 Nov 2025 15:48:30 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6907edce.a70a0220.37351b.0014.GAE@google.com> Subject: [syzbot] [nbd?] KASAN: slab-use-after-free Write in recv_work (3) From: syzbot To: axboe@kernel.dk, josef@toxicpanda.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, nbd@other.debian.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 98bd8b16ae57 Add linux-next specific files for 20251031 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=16802292580000 kernel config: https://syzkaller.appspot.com/x/.config?x=55e89517f3847929 dashboard link: https://syzkaller.appspot.com/bug?extid=56fbf4c7ddf65e95c7cc 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=152a5012580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=108dee14580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/f5d0f0fd772a/disk-98bd8b16.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/ead68b596c79/vmlinux-98bd8b16.xz kernel image: https://storage.googleapis.com/syzbot-assets/6722387b293d/bzImage-98bd8b16.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+56fbf4c7ddf65e95c7cc@syzkaller.appspotmail.com block nbd0: Receive control failed (result -32) block nbd0: shutting down sockets ================================================================== BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:96 [inline] BUG: KASAN: slab-use-after-free in atomic_dec include/linux/atomic/atomic-instrumented.h:592 [inline] BUG: KASAN: slab-use-after-free in recv_work+0x1b78/0x1c60 drivers/block/nbd.c:1028 Write of size 4 at addr ffff88802f2bee78 by task kworker/u9:1/5145 CPU: 0 UID: 0 PID: 5145 Comm: kworker/u9:1 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Workqueue: nbd0-recv recv_work Call Trace: 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 check_region_inline mm/kasan/generic.c:-1 [inline] kasan_check_range+0x2b0/0x2c0 mm/kasan/generic.c:200 instrument_atomic_read_write include/linux/instrumented.h:96 [inline] atomic_dec include/linux/atomic/atomic-instrumented.h:592 [inline] recv_work+0x1b78/0x1c60 drivers/block/nbd.c:1028 process_one_work+0x94a/0x15d0 kernel/workqueue.c:3267 process_scheduled_works kernel/workqueue.c:3350 [inline] worker_thread+0x9b0/0xee0 kernel/workqueue.c:3431 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Allocated by task 5998: 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:397 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:414 kasan_kmalloc include/linux/kasan.h:262 [inline] __kmalloc_cache_noprof+0x3e2/0x700 mm/slub.c:5771 kmalloc_noprof include/linux/slab.h:957 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] nbd_alloc_and_init_config+0x88/0x260 drivers/block/nbd.c:1683 nbd_genl_connect+0x9d7/0x18f0 drivers/block/nbd.c:2145 genl_family_rcv_msg_doit+0x215/0x300 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2550 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0x21c/0x270 net/socket.c:746 ____sys_sendmsg+0x505/0x830 net/socket.c:2634 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2688 __sys_sendmsg net/socket.c:2720 [inline] __do_sys_sendmsg net/socket.c:2725 [inline] __se_sys_sendmsg net/socket.c:2723 [inline] __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2723 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 5145: 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:584 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:2547 [inline] slab_free mm/slub.c:6638 [inline] kfree+0x19a/0x6d0 mm/slub.c:6845 nbd_config_put+0x4a1/0x580 drivers/block/nbd.c:1463 recv_work+0x1b62/0x1c60 drivers/block/nbd.c:1027 process_one_work+0x94a/0x15d0 kernel/workqueue.c:3267 process_scheduled_works kernel/workqueue.c:3350 [inline] worker_thread+0x9b0/0xee0 kernel/workqueue.c:3431 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 The buggy address belongs to the object at ffff88802f2bee00 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 120 bytes inside of freed 256-byte region [ffff88802f2bee00, ffff88802f2bef00) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2f2be head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88801b026b40 dead000000000122 0000000000000000 raw: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88801b026b40 dead000000000122 0000000000000000 head: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000 head: 00fff00000000001 ffffea0000bcaf81 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5937, tgid 5937 (syz-executor), ts 108999640718, free_ts 108976063617 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851 prep_new_page mm/page_alloc.c:1859 [inline] get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3920 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5214 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2479 alloc_slab_page mm/slub.c:3063 [inline] allocate_slab+0x96/0x350 mm/slub.c:3236 new_slab mm/slub.c:3290 [inline] ___slab_alloc+0xe94/0x18a0 mm/slub.c:4659 __slab_alloc+0x65/0x100 mm/slub.c:4778 __slab_alloc_node mm/slub.c:4854 [inline] slab_alloc_node mm/slub.c:5276 [inline] __do_kmalloc_node mm/slub.c:5649 [inline] __kmalloc_noprof+0x47d/0x800 mm/slub.c:5662 kmalloc_noprof include/linux/slab.h:961 [inline] kmalloc_array_noprof include/linux/slab.h:1003 [inline] genl_family_rcv_msg_attrs_parse+0xa3/0x2a0 net/netlink/genetlink.c:940 genl_family_rcv_msg_doit+0xb8/0x300 net/netlink/genetlink.c:1093 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2550 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0x21c/0x270 net/socket.c:746 page last free pid 5937 tgid 5937 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1395 [inline] __free_frozen_pages+0xbc8/0xd30 mm/page_alloc.c:2948 __slab_free+0x2e7/0x390 mm/slub.c:5970 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:349 kasan_slab_alloc include/linux/kasan.h:252 [inline] slab_post_alloc_hook mm/slub.c:4978 [inline] slab_alloc_node mm/slub.c:5288 [inline] kmem_cache_alloc_noprof+0x37d/0x700 mm/slub.c:5295 __kernfs_new_node+0xd7/0x7e0 fs/kernfs/dir.c:637 kernfs_new_node+0x102/0x210 fs/kernfs/dir.c:713 __kernfs_create_file+0x4b/0x2e0 fs/kernfs/file.c:1057 sysfs_add_file_mode_ns+0x238/0x300 fs/sysfs/file.c:313 sysfs_merge_group+0x177/0x310 fs/sysfs/group.c:376 dpm_sysfs_add+0xd2/0x270 drivers/base/power/sysfs.c:704 device_add+0x4d8/0xb80 drivers/base/core.c:3649 wiphy_register+0x1d2e/0x2d20 net/wireless/core.c:1035 ieee80211_register_hw+0x34a7/0x4110 net/mac80211/main.c:1591 mac80211_hwsim_new_radio+0x2f85/0x5340 drivers/net/wireless/virtual/mac80211_hwsim.c:5804 Memory state around the buggy address: ffff88802f2bed00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88802f2bed80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88802f2bee00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88802f2bee80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88802f2bef00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc 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