WARNING in check_buffer

Status: upstream: reported C repro on 2026/09/20 14:21
Subsystems: trace
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+eb74dca0d1eb3ec227a7@syzkaller.appspotmail.com
First crash: 23d, last: 3h54m
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
c7dc5e0c repro-c Reproduced: ✅ ❓ WARNING in check_buffer 2026/10/06 20:47 2026/10/06 20:47 2026/10/06 21:43 f7710056
2e922cda assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ WARNING in check_buffer 2026/09/18 00:34 2026/09/18 00:34 2026/09/18 01:09 8d7d05f1
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [trace?] WARNING in check_buffer 1 (3) 2026/10/06 21:58
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 WARNING in check_buffer origin:lts-only -1 syz, C 9 1d14h 74d 0/3 upstream: reported C repro on 2026/07/27 18:46
linux-6.1 WARNING in check_buffer -1 15 1d04h 74d 0/3 upstream: reported on 2026/07/27 19:37
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/10/06 21:43 14m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 69f80fef3153299d9c72c53d1d71eef6354b6926 report job log log

Sample crash report:
 0x90: [80897807093] delta:0 TIME EXTEND
 0x98:  [80897807093] delta:0 .
expected end:0xb0 last event actually ended at:0xb0
------------[ cut here ]------------
system_state != SYSTEM_BOOTING
WARNING: kernel/trace/ring_buffer.c:4783 at check_buffer.cold+0x1a2/0x1ef kernel/trace/ring_buffer.c:4783, CPU#2: syz-executor270/6036
Modules linked in:
CPU: 2 UID: 0 PID: 6036 Comm: syz-executor270 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:check_buffer.cold+0x1a2/0x1ef kernel/trace/ring_buffer.c:4783
Code: 03 0f b6 14 11 38 d0 7c 04 84 d2 75 5c 8b 2d cc 17 22 10 31 ff 89 ee e8 9f 78 e8 00 85 ed 0f 84 18 13 eb 00 e8 22 7e e8 00 90 <0f> 0b 90 e9 c3 10 eb 00 49 c7 c7 00 5e f6 8b e9 51 fe ff ff e8 38
RSP: 0000:ffffc900037cf9a0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 1ffff920006f9f3a RCX: 0000000000000002
RDX: ffff888021a98000 RSI: ffffffff812327ce RDI: ffff888021a98000
RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000001 R12: 0000000000005c85
R13: ffff88801d6c4000 R14: ffff88801cf70000 R15: ffffffff8bf659a0
FS:  0000000000000000(0000) GS:ffff888096b52000(0063) knlGS:00000000f5e91b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f5e916d8 CR3: 0000000055cc8000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __rb_reserve_next.constprop.0+0x486/0x1640 kernel/trace/ring_buffer.c:4873
 rb_reserve_next_event kernel/trace/ring_buffer.c:5010 [inline]
 ring_buffer_lock_reserve+0x49a/0x1220 kernel/trace/ring_buffer.c:5069
 __trace_buffer_lock_reserve kernel/trace/trace.h:1677 [inline]
 write_marker_to_buffer+0x88/0x5f0 kernel/trace/trace.c:5936
 tracing_mark_write+0x215/0x3b0 kernel/trace/trace.c:6322
 vfs_write+0x2aa/0x1050 fs/read_write.c:685
 ksys_write+0x1f8/0x250 fs/read_write.c:739
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline]
 do_int80_emulation+0x166/0x650 arch/x86/entry/syscall_32.c:166
 asm_int80_emulation+0x1a/0x20 arch/x86/include/asm/idtentry.h:598
RIP: 0023:0xf7ee27eb
Code: 57 56 53 8b 44 24 14 f6 00 08 75 23 8b 44 24 18 8b 5c 24 1c 8b 4c 24 20 8b 54 24 24 8b 74 24 28 8b 7c 24 2c 8b 6c 24 30 cd 80 <5b> 5e 5f 5d c3 5b 5e 5f 5d e9 57 dd ff ff 66 90 66 90 66 90 90 55
RSP: 002b:00000000f5e9161c EFLAGS: 00000246 ORIG_RAX: 0000000000000004
RAX: ffffffffffffffda RBX: 0000000000000007 RCX: 00000000f7f2dde3
RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess):
   0:	57                   	push   %rdi
   1:	56                   	push   %rsi
   2:	53                   	push   %rbx
   3:	8b 44 24 14          	mov    0x14(%rsp),%eax
   7:	f6 00 08             	testb  $0x8,(%rax)
   a:	75 23                	jne    0x2f
   c:	8b 44 24 18          	mov    0x18(%rsp),%eax
  10:	8b 5c 24 1c          	mov    0x1c(%rsp),%ebx
  14:	8b 4c 24 20          	mov    0x20(%rsp),%ecx
  18:	8b 54 24 24          	mov    0x24(%rsp),%edx
  1c:	8b 74 24 28          	mov    0x28(%rsp),%esi
  20:	8b 7c 24 2c          	mov    0x2c(%rsp),%edi
  24:	8b 6c 24 30          	mov    0x30(%rsp),%ebp
  28:	cd 80                	int    $0x80
* 2a:	5b                   	pop    %rbx <-- trapping instruction
  2b:	5e                   	pop    %rsi
  2c:	5f                   	pop    %rdi
  2d:	5d                   	pop    %rbp
  2e:	c3                   	ret
  2f:	5b                   	pop    %rbx
  30:	5e                   	pop    %rsi
  31:	5f                   	pop    %rdi
  32:	5d                   	pop    %rbp
  33:	e9 57 dd ff ff       	jmp    0xffffdd8f
  38:	66 90                	xchg   %ax,%ax
  3a:	66 90                	xchg   %ax,%ax
  3c:	66 90                	xchg   %ax,%ax
  3e:	90                   	nop
  3f:	55                   	push   %rbp

Crashes (23):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/06 21:57 git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 69f80fef3153 6d32eb1f .config console log report C ci-qemu-upstream-386 WARNING in check_buffer
2026/10/01 23:40 upstream d24e8ac715de 6d32eb1f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in check_buffer
2026/09/29 20:06 upstream 6f8319e3e9a4 7808aef4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in check_buffer
2026/09/29 03:34 upstream 72d3fcf802c4 7bf4ea23 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in check_buffer
2026/09/29 03:22 upstream 72d3fcf802c4 7bf4ea23 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in check_buffer
2026/09/24 23:07 upstream f49a343b305c 3c3cdf19 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in check_buffer
2026/09/23 20:36 upstream fe2ec83746e5 0a1606bc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in check_buffer
2026/09/22 19:22 upstream c4e9f74da438 3e2106e5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in check_buffer
2026/09/22 19:22 upstream c4e9f74da438 3e2106e5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in check_buffer
2026/09/19 15:34 upstream 40288c9206c1 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in check_buffer
2026/09/18 12:55 upstream 5dd1818b15d9 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in check_buffer
2026/09/17 19:33 upstream 4982d3552a3b 95928915 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in check_buffer
2026/10/08 13:16 upstream 0c2669a9f4a1 9d4697fa .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in check_buffer
2026/10/05 15:35 upstream 67f0943b394d 1995e6c7 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in check_buffer
2026/09/30 16:57 upstream 551c722f4080 15fb8e5e .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in check_buffer
2026/09/30 16:57 upstream 551c722f4080 15fb8e5e .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in check_buffer
2026/09/18 19:36 upstream 5dd1818b15d9 853b104b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in check_buffer
2026/09/18 05:48 upstream 4982d3552a3b 8d7d05f1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in check_buffer
2026/09/26 21:37 upstream 6812ce4e4379 a3c7249d .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in check_buffer
2026/09/22 19:15 upstream 50d05c7c76c9 3e2106e5 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in check_buffer
2026/09/20 16:33 upstream 50d05c7c76c9 853b104b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in check_buffer
2026/09/16 14:09 upstream 50d05c7c76c9 b0e4c57e .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in check_buffer
2026/10/10 05:12 linux-next becb95e45ef0 a8add9cd .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in check_buffer
* Struck through repros no longer work on HEAD.