UBSAN: shift-out-of-bounds in dbSplit (2)

Status: upstream: reported C repro on 2025/03/09 22:23
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+770402b99e245985119d@syzkaller.appspotmail.com
First crash: 503d, last: 436d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2025/03/10 upstream (ToT) 80e54e84911a C [report] UBSAN: shift-out-of-bounds in dbSplit
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 UBSAN: shift-out-of-bounds in dbSplit -1 C done 18 614d 831d 3/3 fixed on 2025/01/09 09:39
upstream UBSAN: shift-out-of-bounds in dbSplit (2) jfs -1 C error 403 600d 845d 28/29 fixed on 2024/12/16 09:50
upstream UBSAN: shift-out-of-bounds in dbSplit jfs -1 C error done 7 936d 1391d 25/29 fixed on 2024/02/09 18:10
upstream UBSAN: shift-out-of-bounds in dbSplit (3) jfs -1 C 8 137d 451d 29/29 fixed on 2026/05/21 07:50
linux-5.15 UBSAN: shift-out-of-bounds in dbSplit origin:upstream -1 C error 36 64d 831d 0/3 upstream: reported C repro on 2024/04/15 22:09
▶ ▼ Fix bisection attempts (3)
Created Duration User Patch Repo Result
2025/06/18 18:14 17m bisect fix linux-6.1.y error job log
2025/05/15 22:30 1h53m bisect fix linux-6.1.y OK (0) job log log
2025/04/13 23:27 1h20m bisect fix linux-6.1.y OK (0) job log log

Sample crash report:
loop0: detected capacity change from 0 to 32768
================================================================================
UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.c:2644:11
shift exponent 121 is too large for 32-bit type 'int'
CPU: 0 PID: 4245 Comm: syz-executor460 Not tainted 6.1.130-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 ubsan_epilogue lib/ubsan.c:151 [inline]
 __ubsan_handle_shift_out_of_bounds+0x3bf/0x420 lib/ubsan.c:321
 dbSplit+0x21a/0x220 fs/jfs/jfs_dmap.c:2644
 dbAllocBits+0x4e0/0x9f0 fs/jfs/jfs_dmap.c:2196
 dbAllocDmap fs/jfs/jfs_dmap.c:2037 [inline]
 dbAllocDmapLev+0x24c/0x490 fs/jfs/jfs_dmap.c:1991
 dbAllocCtl+0x147/0x9a0 fs/jfs/jfs_dmap.c:1828
 dbAllocAG+0x28b/0x10b0 fs/jfs/jfs_dmap.c:1364
 dbAlloc+0x654/0xc90 fs/jfs/jfs_dmap.c:888
 dtSplitUp fs/jfs/jfs_dtree.c:981 [inline]
 dtInsert+0xd76/0x6c80 fs/jfs/jfs_dtree.c:870
 jfs_create+0x7b2/0xbb0 fs/jfs/namei.c:137
 lookup_open fs/namei.c:3482 [inline]
 open_last_lookups fs/namei.c:3550 [inline]
 path_openat+0x12f1/0x2e60 fs/namei.c:3780
 do_filp_open+0x230/0x480 fs/namei.c:3810
 do_sys_openat2+0x13b/0x4f0 fs/open.c:1318
 do_sys_open fs/open.c:1334 [inline]
 __do_sys_open fs/open.c:1342 [inline]
 __se_sys_open fs/open.c:1338 [inline]
 __x64_sys_open+0x221/0x270 fs/open.c:1338
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7faea8b329b9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 17 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffa733f838 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 633d73726f727265 RCX: 00007faea8b329b9
RDX: 0000000000000000 RSI: 0000000000000040 RDI: 0000400000000400
RBP: 00007faea8bab610 R08: 00000000000060cc R09: 0000000000000000
R10: 00007fffa733f700 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fffa733fa08 R14: 0000000000000001 R15: 0000000000000001
 </TASK>
================================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/03/09 22:23 linux-6.1.y 6ae7ac5c4251 163f510d .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-1-kasan UBSAN: shift-out-of-bounds in dbSplit
* Struck through repros no longer work on HEAD.