syzbot


general protection fault in btrfs_encoded_read_endio

Status: upstream: reported on 2026/04/25 03:13
Reported-by: syzbot+687ff8c95070d957cb3f@syzkaller.appspotmail.com
First crash: 20h12m, last: 20h12m

Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc0021790f08: 0000 [#1] PREEMPT SMP KASAN
KASAN: probably user-memory-access in range [0x000000010bc87840-0x000000010bc87847]
CPU: 1 PID: 11 Comm: kworker/u4:0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: btrfs-endio btrfs_end_bio_work
RIP: 0010:__wake_up_common+0x23c/0x4e0 kernel/sched/wait.c:100
Code: 24 00 00 00 00 49 83 c5 40 4d 39 ef 0f 84 ed 01 00 00 45 31 f6 eb 09 4d 39 ef 0f 84 df 01 00 00 4c 89 fd 4c 89 f8 48 c1 e8 03 <80> 3c 10 00 74 12 48 89 ef e8 36 ca 79 00 48 ba 00 00 00 00 00 fc
RSP: 0018:ffffc90000107898 EFLAGS: 00010002
RAX: 0000000021790f08 RBX: 0000000000000001 RCX: f8eda4d6cde3a300
RDX: dffffc0000000000 RSI: ffffffff8acadb60 RDI: ffffffff8b1c8e60
RBP: 000000010bc87840 R08: 0000000000000000 R09: ffffc90000107940
R10: dffffc0000000000 R11: fffff52000020efc R12: ffffc9000bc87800
R13: ffffc9000bc87840 R14: 0000000000000000 R15: 000000010bc87840
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2d61eff8 CR3: 00000000601c9000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 __wake_up_common_lock kernel/sched/wait.c:138 [inline]
 __wake_up+0x125/0x1a0 kernel/sched/wait.c:160
 btrfs_encoded_read_endio+0xd1/0x130 fs/btrfs/inode.c:10060
 btrfs_check_read_bio+0xf08/0x1500 fs/btrfs/bio.c:325
 process_one_work kernel/workqueue.c:2653 [inline]
 process_scheduled_works+0xa5d/0x15d0 kernel/workqueue.c:2730
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2811
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__wake_up_common+0x23c/0x4e0 kernel/sched/wait.c:100
Code: 24 00 00 00 00 49 83 c5 40 4d 39 ef 0f 84 ed 01 00 00 45 31 f6 eb 09 4d 39 ef 0f 84 df 01 00 00 4c 89 fd 4c 89 f8 48 c1 e8 03 <80> 3c 10 00 74 12 48 89 ef e8 36 ca 79 00 48 ba 00 00 00 00 00 fc
RSP: 0018:ffffc90000107898 EFLAGS: 00010002
RAX: 0000000021790f08 RBX: 0000000000000001 RCX: f8eda4d6cde3a300
RDX: dffffc0000000000 RSI: ffffffff8acadb60 RDI: ffffffff8b1c8e60
RBP: 000000010bc87840 R08: 0000000000000000 R09: ffffc90000107940
R10: dffffc0000000000 R11: fffff52000020efc R12: ffffc9000bc87800
R13: ffffc9000bc87840 R14: 0000000000000000 R15: 000000010bc87840
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2d61eff8 CR3: 00000000601c9000 CR4: 00000000003506e0
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	00 00                	add    %al,(%rax)
   2:	00 00                	add    %al,(%rax)
   4:	49 83 c5 40          	add    $0x40,%r13
   8:	4d 39 ef             	cmp    %r13,%r15
   b:	0f 84 ed 01 00 00    	je     0x1fe
  11:	45 31 f6             	xor    %r14d,%r14d
  14:	eb 09                	jmp    0x1f
  16:	4d 39 ef             	cmp    %r13,%r15
  19:	0f 84 df 01 00 00    	je     0x1fe
  1f:	4c 89 fd             	mov    %r15,%rbp
  22:	4c 89 f8             	mov    %r15,%rax
  25:	48 c1 e8 03          	shr    $0x3,%rax
* 29:	80 3c 10 00          	cmpb   $0x0,(%rax,%rdx,1) <-- trapping instruction
  2d:	74 12                	je     0x41
  2f:	48 89 ef             	mov    %rbp,%rdi
  32:	e8 36 ca 79 00       	call   0x79ca6d
  37:	48                   	rex.W
  38:	ba 00 00 00 00       	mov    $0x0,%edx
  3d:	00 fc                	add    %bh,%ah

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/25 03:13 linux-6.6.y 9760bf04666d 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan general protection fault in btrfs_encoded_read_endio
* Struck through repros no longer work on HEAD.