syzbot


general protection fault in __find_get_block

Status: upstream: reported on 2026/05/29 12:56
Reported-by: syzbot+9c5a581093bc5e88a089@syzkaller.appspotmail.com
First crash: 9d07h, last: 9d07h
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 general protection fault in __find_get_block 2 1 2116d 2116d 0/1 auto-closed as invalid on 2020/12/19 07:08
linux-4.19 general protection fault in __find_get_block (2) 2 1 1667d 1667d 0/1 auto-closed as invalid on 2022/03/13 03:33
linux-4.14 general protection fault in __find_get_block 2 1 2200d 2200d 0/1 auto-closed as invalid on 2020/09/26 01:39
upstream KASAN: slab-use-after-free Read in __find_get_block exfat 19 1 526d 513d 0/29 auto-obsoleted due to no activity on 2025/04/07 06:59

Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]
CPU: 1 PID: 4278 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:__find_get_block_slow fs/buffer.c:191 [inline]
RIP: 0010:__find_get_block+0x2e2/0xec0 fs/buffer.c:1307
Code: d8 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 48 8b 44 24 28 48 8d 58 30 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 df e8 20 85 e2 ff 4c 8b 23 49 8d 7c 24 30
RSP: 0018:ffffc90003e07660 EFLAGS: 00010206
RAX: 0000000000000006 RBX: 0000000000000030 RCX: dffffc0000000000
RDX: dffffc0000000000 RSI: ffffffff8a8c19a0 RDI: ffffffff8adf1b60
RBP: ffffc90003e07798 R08: ffffffff90afd39f R09: 1ffffffff215fa73
R10: dffffc0000000000 R11: fffffbfff215fa74 R12: fffffffffffffff1
R13: 0000000000000000 R14: 0000000000036af0 R15: 000000000000004c
FS:  000055558bb1b500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb7b0dab000 CR3: 000000005cc86000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 jbd2_journal_cancel_revoke+0x3e2/0x470 fs/jbd2/revoke.c:469
 do_get_write_access+0xb4f/0xf60 fs/jbd2/transaction.c:1160
 jbd2_journal_get_write_access+0x108/0x140 fs/jbd2/transaction.c:1250
 __ocfs2_journal_access+0x4de/0x8c0 fs/ocfs2/journal.c:727
 ocfs2_shutdown_local_alloc+0x428/0xaa0 fs/ocfs2/localalloc.c:432
 ocfs2_dismount_volume+0x1ff/0x940 fs/ocfs2/super.c:1882
 generic_shutdown_super+0x130/0x340 fs/super.c:501
 kill_block_super+0x7c/0xe0 fs/super.c:1470
 deactivate_locked_super+0x93/0xf0 fs/super.c:332
 cleanup_mnt+0x42c/0x4b0 fs/namespace.c:1191
 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:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f801ef9e097
Code: a2 c7 05 5c 06 25 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffe6b4db428 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f801f0321ca RCX: 00007f801ef9e097
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffe6b4db4e0
RBP: 00007ffe6b4db4e0 R08: 00007ffe6b4dc4e0 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe6b4dc570
R13: 00007f801f0321ca R14: 000000000003b36a R15: 00007ffe6b4dc5b0
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__find_get_block_slow fs/buffer.c:191 [inline]
RIP: 0010:__find_get_block+0x2e2/0xec0 fs/buffer.c:1307
Code: d8 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 48 8b 44 24 28 48 8d 58 30 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 df e8 20 85 e2 ff 4c 8b 23 49 8d 7c 24 30
RSP: 0018:ffffc90003e07660 EFLAGS: 00010206
RAX: 0000000000000006 RBX: 0000000000000030 RCX: dffffc0000000000
RDX: dffffc0000000000 RSI: ffffffff8a8c19a0 RDI: ffffffff8adf1b60
RBP: ffffc90003e07798 R08: ffffffff90afd39f R09: 1ffffffff215fa73
R10: dffffc0000000000 R11: fffffbfff215fa74 R12: fffffffffffffff1
R13: 0000000000000000 R14: 0000000000036af0 R15: 000000000000004c
FS:  000055558bb1b500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4095bea2f8 CR3: 000000005cc86000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	d8 48 8d             	fmuls  -0x73(%rax)
   3:	65 d8 5b 41          	fcomps %gs:0x41(%rbx)
   7:	5c                   	pop    %rsp
   8:	41 5d                	pop    %r13
   a:	41 5e                	pop    %r14
   c:	41 5f                	pop    %r15
   e:	5d                   	pop    %rbp
   f:	c3                   	ret
  10:	48 8b 44 24 28       	mov    0x28(%rsp),%rax
  15:	48 8d 58 30          	lea    0x30(%rax),%rbx
  19:	48 89 d8             	mov    %rbx,%rax
  1c:	48 c1 e8 03          	shr    $0x3,%rax
  20:	48 b9 00 00 00 00 00 	movabs $0xdffffc0000000000,%rcx
  27:	fc ff df
* 2a:	80 3c 08 00          	cmpb   $0x0,(%rax,%rcx,1) <-- trapping instruction
  2e:	74 08                	je     0x38
  30:	48 89 df             	mov    %rbx,%rdi
  33:	e8 20 85 e2 ff       	call   0xffe28558
  38:	4c 8b 23             	mov    (%rbx),%r12
  3b:	49 8d 7c 24 30       	lea    0x30(%r12),%rdi

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/29 12:55 linux-6.1.y dcbcab9d7079 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in __find_get_block
* Struck through repros no longer work on HEAD.