WARNING in check_buffer

Status: upstream: reported on 2026/07/27 19:37
Reported-by: syzbot+c202c0341faf948688f8@syzkaller.appspotmail.com
First crash: 58d, last: 22h20m
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in check_buffer trace prio:low -1 10 1d00h 3d05h 0/29 upstream: reported on 2026/09/20 14:21
linux-5.15 WARNING in check_buffer origin:lts-only -1 syz, C 6 21h55m 58d 0/3 upstream: reported C repro on 2026/07/27 18:46

Sample crash report:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 8140 at kernel/trace/ring_buffer.c:3526 check_buffer+0x88a/0x930 kernel/trace/ring_buffer.c:3526
Modules linked in:
CPU: 0 PID: 8140 Comm: udevd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:check_buffer+0x88a/0x930 kernel/trace/ring_buffer.c:3526
Code: 4c 89 ee e8 88 26 a2 08 48 c7 c7 20 04 c6 96 be 04 00 00 00 e8 67 31 4e 00 f0 ff 0d 40 bc 40 15 e9 91 fe ff ff e8 f6 ea fc ff <0f> 0b e9 e2 fe ff ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 20 f8 ff
RSP: 0018:ffffc900035571c0 EFLAGS: 00010093
RAX: ffffffff818547ea RBX: 0000000000000003 RCX: ffff88802a060000
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000000
RBP: ffffc90003557378 R08: ffff888017478807 R09: 1ffff11002e8f100
R10: dffffc0000000000 R11: ffffed1002e8f101 R12: 0000000004ccb519
R13: 0000000000000034 R14: ffff888017478800 R15: dffffc0000000000
FS:  00007fa59eb4b880(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa59eb3f000 CR3: 0000000077e1d000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __rb_reserve_next+0x4d9/0xd00 kernel/trace/ring_buffer.c:3622
 rb_reserve_next_event kernel/trace/ring_buffer.c:3757 [inline]
 ring_buffer_lock_reserve+0xafa/0xf10 kernel/trace/ring_buffer.c:3816
 __trace_buffer_lock_reserve kernel/trace/trace.c:956 [inline]
 trace_event_buffer_lock_reserve+0x1ce/0x6f0 kernel/trace/trace.c:2843
 trace_event_buffer_reserve+0x2a8/0x3d0 kernel/trace/trace_events.c:647
 do_trace_event_raw_event_lock_acquire include/trace/events/lock.h:24 [inline]
 trace_event_raw_event_lock_acquire+0x124/0x290 include/trace/events/lock.h:24
 trace_lock_acquire include/trace/events/lock.h:24 [inline]
 lock_acquire+0x452/0x4a0 kernel/locking/lockdep.c:5649
 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
 _raw_spin_lock_irq+0xab/0xf0 kernel/locking/spinlock.c:170
 spin_lock_irq include/linux/spinlock.h:376 [inline]
 filemap_remove_folio+0xe3/0x2c0 mm/filemap.c:254
 truncate_inode_folio+0x59/0x70 mm/truncate.c:195
 shmem_undo_range+0x554/0x21d0 mm/shmem.c:942
 shmem_truncate_range mm/shmem.c:1062 [inline]
 shmem_evict_inode+0x225/0x9f0 mm/shmem.c:1171
 evict+0x4b6/0x8b0 fs/inode.c:705
 __dentry_kill+0x412/0x630 fs/dcache.c:611
 dentry_kill+0xb8/0x290 fs/dcache.c:-1
 dput+0xfa/0x1d0 fs/dcache.c:918
 __fput+0x597/0x8b0 fs/file_table.c:328
 task_work_run+0x1d0/0x260 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:180
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:213
 __syscall_exit_to_user_mode_work kernel/entry/common.c:295 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:306
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa59e4a7407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007fff27666b60 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007fa59eb4b880 RCX: 00007fa59e4a7407
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000008
RBP: 00007fa59eb4b6e8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000002
R13: 000055ee87c21410 R14: 0000000000000008 R15: 000055ee87c23320
 </TASK>

Crashes (14):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/22 21:37 linux-6.1.y 1a8763b93150 5207b90e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in check_buffer
2026/09/11 13:00 linux-6.1.y cf82dcca9634 b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in check_buffer
2026/09/09 05:34 linux-6.1.y cf82dcca9634 8387c273 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in check_buffer
2026/08/18 01:24 linux-6.1.y e4f7d8be268e 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in check_buffer
2026/08/11 18:54 linux-6.1.y e4f7d8be268e 71790083 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in check_buffer
2026/08/08 05:38 linux-6.1.y e4f7d8be268e 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in check_buffer
2026/08/08 05:37 linux-6.1.y e4f7d8be268e 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in check_buffer
2026/07/27 19:40 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in check_buffer
2026/07/27 19:40 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in check_buffer
2026/07/27 19:40 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in check_buffer
2026/07/27 19:40 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in check_buffer
2026/07/27 19:36 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in check_buffer
2026/07/27 19:36 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in check_buffer
2026/07/27 19:36 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in check_buffer
* Struck through repros no longer work on HEAD.