UBSAN: shift-out-of-bounds in dbMount

Status: auto-obsoleted due to no activity on 2023/06/15 19:41
Subsystems: jfs
[Documentation on labels]
First crash: 465d, last: 370d
Cause bisection: introduced by (bisect log) [merge commit]:
commit 01bf246a20c7664ae41cdbefd0314d0fb67d63e9
Author: David S. Miller <>
Date: Wed Sep 21 12:50:03 2022 +0000

  Merge branch 'net-dev_err_probe'

Crash: KASAN: use-after-free Read in copy_page_from_iter_atomic (log)
Repro: C syz .config
Fix bisection: fixed by (bisect log) :
commit fad376fce0af58deebc5075b8539dc05bf639af3
Author: Liu Shixin via Jfs-discussion <>
Date: Thu Nov 3 03:01:59 2022 +0000

  fs/jfs: fix shift exponent db_agl2size negative

Discussions (1)
Title Replies (including bot) Last reply
[syzbot] UBSAN: shift-out-of-bounds in dbMount 0 (2) 2023/03/18 02:27
Last patch testing requests (1)
Created Duration User Patch Repo Result
2023/05/15 06:59 23m retest repro linux-next OK log

Sample crash report:
loop0: detected capacity change from 0 to 31132
UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.c:201:29
shift exponent -1 is negative
CPU: 1 PID: 5248 Comm: syz-executor395 Not tainted 6.2.0-rc7-syzkaller-00013-g513c1a3d3f19 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
 ubsan_epilogue+0xa/0x31 lib/ubsan.c:151
 __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x187 lib/ubsan.c:321
 dbMount.cold+0x17/0x38 fs/jfs/jfs_dmap.c:201
 jfs_mount+0x267/0x7b0 fs/jfs/jfs_mount.c:121
 jfs_fill_super+0x5a8/0xc80 fs/jfs/super.c:556
 mount_bdev+0x351/0x410 fs/super.c:1359
 legacy_get_tree+0x109/0x220 fs/fs_context.c:610
 vfs_get_tree+0x8d/0x2f0 fs/super.c:1489
 do_new_mount fs/namespace.c:3145 [inline]
 path_mount+0x132a/0x1e20 fs/namespace.c:3475
 do_mount fs/namespace.c:3488 [inline]
 __do_sys_mount fs/namespace.c:3697 [inline]
 __se_sys_mount fs/namespace.c:3674 [inline]
 __x64_sys_mount+0x283/0x300 fs/namespace.c:3674
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
RIP: 0033:0x7efd19257c5a
Code: 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d2 e8 a8 00 00 00 0f 1f 84 00 00 00 00 00 49 89 ca b8 a5 00 00 00 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:00007efd19202118 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007efd192026b8 RCX: 00007efd19257c5a
RDX: 0000000020005e00 RSI: 0000000020000000 RDI: 00007efd19202170
RBP: 0000000000000005 R08: 00007efd192021b0 R09: 0000000000005f06
R10: 0000000000000000 R11: 0000000000000286 R12: 0000000020005e00
R13: 0000000020000000 R14: 0000000000005f0c R15: 0000000020000100

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/02/08 06:54 upstream 513c1a3d3f19 15c3d445 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2] ci-upstream-kasan-gce-root UBSAN: shift-out-of-bounds in dbMount
2022/11/13 04:25 linux-next f8f60f322f06 3ead01ad .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-linux-next-kasan-gce-root UBSAN: shift-out-of-bounds in dbMount
2023/02/15 19:40 upstream e1c04510f521 6be0f1f5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs UBSAN: shift-out-of-bounds in dbMount
2023/01/31 18:30 upstream 22b8077d0fce 9dfcf09c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root UBSAN: shift-out-of-bounds in dbMount
2023/01/24 04:28 upstream 7bf70dbb1882 9dfcf09c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs UBSAN: shift-out-of-bounds in dbMount
* Struck through repros no longer work on HEAD.