syzbot


general protection fault in reiserfs_get_block

Status: upstream: reported C repro on 2025/12/09 12:02
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+fb2b35129077a32ad1cc@syzkaller.appspotmail.com
First crash: 9d13h, last: 7d00h
Bug presence (2)
Date Name Commit Repro Result
2025/12/11 linux-6.6.y (ToT) 5fa4793a2d2d C [report] general protection fault in reiserfs_get_block
2025/12/11 upstream (ToT) d358e5254674 C Didn't crash
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 BUG: unable to handle kernel paging request in reiserfs_get_block origin:upstream missing-backport 8 C done 7 68d 577d 0/3 upstream: reported C repro on 2024/05/20 22:59
linux-5.15 general protection fault in reiserfs_get_block origin:lts-only 8 C error 13 15d 464d 0/3 upstream: reported C repro on 2024/09/10 09:00
upstream general protection fault in reiserfs_get_block fs 2 2 1077d 1074d 0/29 auto-obsoleted due to no activity on 2023/05/06 14:40

Sample crash report:
REISERFS warning (device loop0): vs-13060 reiserfs_update_sd_size: stat data of object [2 5 0x0 SD] (nlink == 1) not found (pos 2)
general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 0 PID: 5928 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:reiserfs_get_block+0x1612/0x3ed0 fs/reiserfs/inode.c:1052
Code: 5f 04 00 00 e8 8f c0 65 ff 4d 89 f0 e9 0b 02 00 00 44 8b bc 24 40 03 00 00 4c 89 74 24 38 4d 8d 74 9e fc 4c 89 f0 48 c1 e8 03 <42> 0f b6 04 20 84 c0 0f 85 63 0d 00 00 4c 89 fb 45 89 3e 48 8b 44
RSP: 0018:ffffc9000486f2a0 EFLAGS: 00010203
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffff88801fadbc00
RDX: 0000000000000000 RSI: 00000000000003f4 RDI: 0000000000000000
RBP: ffffc9000486f810 R08: ffffc9000486f77f R09: 0000000000000000
R10: ffffc9000486f760 R11: fffff5200090def0 R12: dffffc0000000000
R13: 00000000000003f4 R14: 000000000000000c R15: 0000000000000217
FS:  00005555726e9500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6bd45a4000 CR3: 0000000023bde000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 __block_write_begin_int+0x566/0x1ad0 fs/buffer.c:2124
 reiserfs_write_begin+0x20a/0x4c0 fs/reiserfs/inode.c:2771
 generic_perform_write+0x2fb/0x5b0 mm/filemap.c:4031
 generic_file_write_iter+0xaf/0x2e0 mm/filemap.c:4152
 do_iter_readv_writev fs/read_write.c:-1 [inline]
 do_iter_write+0x79a/0xc70 fs/read_write.c:860
 vfs_writev fs/read_write.c:933 [inline]
 do_pwritev+0x205/0x340 fs/read_write.c:1030
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff85c78f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffda3ce7c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000148
RAX: ffffffffffffffda RBX: 00007ff85c9e5fa0 RCX: 00007ff85c78f749
RDX: 0000000000000001 RSI: 00002000000001c0 RDI: 0000000000000006
RBP: 00007ff85c813f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000e7b R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff85c9e5fa0 R14: 00007ff85c9e5fa0 R15: 0000000000000006
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:reiserfs_get_block+0x1612/0x3ed0 fs/reiserfs/inode.c:1052
Code: 5f 04 00 00 e8 8f c0 65 ff 4d 89 f0 e9 0b 02 00 00 44 8b bc 24 40 03 00 00 4c 89 74 24 38 4d 8d 74 9e fc 4c 89 f0 48 c1 e8 03 <42> 0f b6 04 20 84 c0 0f 85 63 0d 00 00 4c 89 fb 45 89 3e 48 8b 44
RSP: 0018:ffffc9000486f2a0 EFLAGS: 00010203
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffff88801fadbc00
RDX: 0000000000000000 RSI: 00000000000003f4 RDI: 0000000000000000
RBP: ffffc9000486f810 R08: ffffc9000486f77f R09: 0000000000000000
R10: ffffc9000486f760 R11: fffff5200090def0 R12: dffffc0000000000
R13: 00000000000003f4 R14: 000000000000000c R15: 0000000000000217
FS:  00005555726e9500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6bd45a4000 CR3: 0000000023bde000 CR4: 00000000003506f0
----------------
Code disassembly (best guess):
   0:	5f                   	pop    %rdi
   1:	04 00                	add    $0x0,%al
   3:	00 e8                	add    %ch,%al
   5:	8f c0                	pop    %rax
   7:	65 ff 4d 89          	decl   %gs:-0x77(%rbp)
   b:	f0 e9 0b 02 00 00    	lock jmp 0x21c
  11:	44 8b bc 24 40 03 00 	mov    0x340(%rsp),%r15d
  18:	00
  19:	4c 89 74 24 38       	mov    %r14,0x38(%rsp)
  1e:	4d 8d 74 9e fc       	lea    -0x4(%r14,%rbx,4),%r14
  23:	4c 89 f0             	mov    %r14,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 0f b6 04 20       	movzbl (%rax,%r12,1),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	0f 85 63 0d 00 00    	jne    0xd9a
  37:	4c 89 fb             	mov    %r15,%rbx
  3a:	45 89 3e             	mov    %r15d,(%r14)
  3d:	48                   	rex.W
  3e:	8b                   	.byte 0x8b
  3f:	44                   	rex.R

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/09 14:29 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-6-kasan general protection fault in reiserfs_get_block
2025/12/09 13:40 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-6-kasan general protection fault in reiserfs_get_block
2025/12/09 12:52 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-6-kasan general protection fault in reiserfs_get_block
2025/12/12 00:35 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan general protection fault in reiserfs_get_block
2025/12/09 12:02 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan general protection fault in reiserfs_get_block
2025/12/09 12:02 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan general protection fault in reiserfs_get_block
* Struck through repros no longer work on HEAD.