syzbot


kernel BUG in dbFindBits

Status: upstream: reported C repro on 2025/12/12 08:26
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+3275c7b01b736a8a8d1f@syzkaller.appspotmail.com
First crash: 4d12h, last: 3d03h
Bug presence (2)
Date Name Commit Repro Result
2025/12/13 linux-6.6.y (ToT) 5fa4793a2d2d C [report] kernel BUG in dbFindBits
2025/12/13 upstream (ToT) 9d9c1cfec01c C Didn't crash
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream kernel BUG in dbFindLeaf jfs -1 C inconclusive 5800 1h32m 1177d 0/29 upstream: reported C repro on 2022/09/26 11:46
linux-6.1 kernel BUG in dbFindBits origin:upstream -1 C error 61 14d 755d 0/3 upstream: reported C repro on 2023/11/22 10:15
linux-5.15 kernel BUG in dbFindBits origin:upstream -1 C 148 12d 639d 0/3 upstream: reported C repro on 2024/03/17 13:21

Sample crash report:
BUG at fs/jfs/jfs_dmap.c:3036 assert(bitno < 32)
------------[ cut here ]------------
kernel BUG at fs/jfs/jfs_dmap.c:3036!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 6368 Comm: syz.1.92 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:dbFindBits+0x193/0x1a0 fs/jfs/jfs_dmap.c:3036
Code: f3 98 5e 07 0f 0b e8 4c fe 87 fe 48 c7 c7 a0 cd e3 8a 48 c7 c6 e0 ca e3 8a ba dc 0b 00 00 48 c7 c1 a0 d5 e3 8a e8 cd 98 5e 07 <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 55 41 57 41 56 41 55 41 54
RSP: 0018:ffffc9000c0cece8 EFLAGS: 00010246
RAX: 0000000000000030 RBX: 0000000000000000 RCX: b9feb705a667c500
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 00000000ffffffff R08: ffffc9000c0ce9e7 R09: 1ffff92001819d3c
R10: dffffc0000000000 R11: fffff52001819d3d R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000020
FS:  00007fc33e96d6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa705198000 CR3: 00000000259c2000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 dbAllocDmapLev+0x169/0x3c0 fs/jfs/jfs_dmap.c:1985
 dbAllocCtl+0x148/0x9b0 fs/jfs/jfs_dmap.c:1825
 dbAllocAG+0x1e7/0xfe0 fs/jfs/jfs_dmap.c:1353
 dbAlloc+0x5a7/0xba0 fs/jfs/jfs_dmap.c:877
 xtSplitUp+0x497/0x1f30 fs/jfs/jfs_xtree.c:745
 xtInsert+0x3ef/0xe00 fs/jfs/jfs_xtree.c:593
 extAlloc+0x9fa/0xf30 fs/jfs/jfs_extent.c:145
 jfs_get_block+0x347/0xab0 fs/jfs/inode.c:254
 get_more_blocks fs/direct-io.c:647 [inline]
 do_direct_IO fs/direct-io.c:935 [inline]
 __blockdev_direct_IO+0x1679/0x3420 fs/direct-io.c:1248
 blockdev_direct_IO include/linux/fs.h:3047 [inline]
 jfs_direct_IO+0x11b/0x220 fs/jfs/inode.c:337
 generic_file_direct_write+0x1d4/0x3e0 mm/filemap.c:3956
 __generic_file_write_iter+0x11b/0x230 mm/filemap.c:4112
 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: 0033:0x7fc33db8f749
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:00007fc33e96d038 EFLAGS: 00000246 ORIG_RAX: 0000000000000148
RAX: ffffffffffffffda RBX: 00007fc33dde5fa0 RCX: 00007fc33db8f749
RDX: 0000000000000001 RSI: 0000200000000240 RDI: 0000000000000006
RBP: 00007fc33dc13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000007800 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc33dde6038 R14: 00007fc33dde5fa0 R15: 00007fff84294f88
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dbFindBits+0x193/0x1a0 fs/jfs/jfs_dmap.c:3036
Code: f3 98 5e 07 0f 0b e8 4c fe 87 fe 48 c7 c7 a0 cd e3 8a 48 c7 c6 e0 ca e3 8a ba dc 0b 00 00 48 c7 c1 a0 d5 e3 8a e8 cd 98 5e 07 <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 55 41 57 41 56 41 55 41 54
RSP: 0018:ffffc9000c0cece8 EFLAGS: 00010246
RAX: 0000000000000030 RBX: 0000000000000000 RCX: b9feb705a667c500
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 00000000ffffffff R08: ffffc9000c0ce9e7 R09: 1ffff92001819d3c
R10: dffffc0000000000 R11: fffff52001819d3d R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000020
FS:  00007fc33e96d6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2b8b7fe000 CR3: 00000000259c2000 CR4: 00000000003506f0

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/12 21:39 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 kernel BUG in dbFindBits
2025/12/12 17:37 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 kernel BUG in dbFindBits
2025/12/12 10:54 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-6-kasan kernel BUG in dbFindBits
2025/12/12 08:25 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan kernel BUG in dbFindBits
* Struck through repros no longer work on HEAD.