linux-kernel - Re: [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbSplit (3)

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Message-ID: <68d9970b.050a0220.1696c6.0008.GAE@google.com>
Date: Sun, 28 Sep 2025 13:14:03 -0700
From: syzbot <syzbot+4c1966e88c28fa96e053@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com, 
	xandfury@...il.com
Subject: Re: [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbSplit (3)

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
UBSAN: shift-out-of-bounds in dbSplit

loop0: detected capacity change from 0 to 32768
------------[ cut here ]------------
UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.c:2641:11
shift exponent 110 is too large for 32-bit type 'int'
CPU: 0 UID: 0 PID: 5828 Comm: syz.0.16 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x40 lib/ubsan.c:233
 __ubsan_handle_shift_out_of_bounds+0x386/0x410 lib/ubsan.c:494
 dbSplit+0x1f8/0x200 fs/jfs/jfs_dmap.c:2641
 dbAdjCtl+0x34c/0xa20 fs/jfs/jfs_dmap.c:2533
 dbAllocDmap fs/jfs/jfs_dmap.c:2044 [inline]
 dbAllocNear+0x2ee/0x3d0 fs/jfs/jfs_dmap.c:1247
 dbAlloc+0x933/0xba0 fs/jfs/jfs_dmap.c:832
 ea_write+0x374/0xdd0 fs/jfs/xattr.c:232
 ea_put fs/jfs/xattr.c:619 [inline]
 __jfs_setxattr+0xa01/0x1120 fs/jfs/xattr.c:792
 __jfs_xattr_set+0xda/0x170 fs/jfs/xattr.c:941
 __vfs_setxattr+0x43c/0x480 fs/xattr.c:200
 __vfs_setxattr_noperm+0x12d/0x660 fs/xattr.c:234
 vfs_setxattr+0x16b/0x2f0 fs/xattr.c:321
 do_setxattr fs/xattr.c:636 [inline]
 filename_setxattr+0x274/0x600 fs/xattr.c:665
 path_setxattrat+0x364/0x3a0 fs/xattr.c:713
 __do_sys_lsetxattr fs/xattr.c:754 [inline]
 __se_sys_lsetxattr fs/xattr.c:750 [inline]
 __x64_sys_lsetxattr+0xbf/0xe0 fs/xattr.c:750
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f643b38e969
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:00007f643c1ce038 EFLAGS: 00000246 ORIG_RAX: 00000000000000bd
RAX: ffffffffffffffda RBX: 00007f643b5b5fa0 RCX: 00007f643b38e969
RDX: 0000000000000000 RSI: 0000200000000200 RDI: 0000200000000040
RBP: 00007f643b410ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f643b5b5fa0 R15: 00007fff5f732f08
 </TASK>
---[ end trace ]---


Tested on:

commit:         8f973663 Merge tag 'trace-v6.17-rc7' of git://git.kern..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=154abf12580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=71b8dca8b0315854
dashboard link: https://syzkaller.appspot.com/bug?extid=4c1966e88c28fa96e053
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Note: no patches were applied.