Re: [syzbot] [jfs?] UBSAN: array-index-out-of-bounds in dbFindLeaf

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    e4cf7c25bae5 Merge tag 'kbuild-fixes-v6.2' of git://git.ke..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=141a6274480000
kernel config:  https://syzkaller.appspot.com/x/.config?x=68e0be42c8ee4bb4
dashboard link: https://syzkaller.appspot.com/bug?extid=aea1ad91e854d0a83e04
compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10faef4c480000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13170968480000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0a2dc7ed8cf1/disk-e4cf7c25.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b35476d531fc/vmlinux-e4cf7c25.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a66192aa25a5/bzImage-e4cf7c25.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/78eabe0740c8/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+aea1ad91e854d0a83e04@xxxxxxxxxxxxxxxxxxxxxxxxx

loop0: detected capacity change from 0 to 32768
================================================================================
UBSAN: array-index-out-of-bounds in fs/jfs/jfs_dmap.c:2941:16
index 1381 is out of range for type 's8 [1365]'
CPU: 0 PID: 5067 Comm: syz-executor239 Not tainted 6.2.0-rc1-syzkaller-00095-ge4cf7c25bae5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1b1/0x290 lib/dump_stack.c:106
 ubsan_epilogue lib/ubsan.c:151 [inline]
 __ubsan_handle_out_of_bounds+0xe0/0x110 lib/ubsan.c:282
 dbFindLeaf+0x30a/0x440 fs/jfs/jfs_dmap.c:2941
 dbAllocDmapLev+0xa9/0x420 fs/jfs/jfs_dmap.c:1952
 dbAllocCtl+0x113/0x970 fs/jfs/jfs_dmap.c:1808
 dbAllocAG+0x28b/0x1100 fs/jfs/jfs_dmap.c:1349
 dbAlloc+0x661/0xc90 fs/jfs/jfs_dmap.c:873
 dtSplitUp fs/jfs/jfs_dtree.c:974 [inline]
 dtInsert+0xc0e/0x6b80 fs/jfs/jfs_dtree.c:863
 jfs_mkdir+0x757/0xb00 fs/jfs/namei.c:270
 vfs_mkdir+0x3b3/0x590 fs/namei.c:4036
 do_mkdirat+0x25b/0x530 fs/namei.c:4061
 __do_sys_mkdirat fs/namei.c:4076 [inline]
 __se_sys_mkdirat fs/namei.c:4074 [inline]
 __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4074
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f2ba532cb29
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 14 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffd3c83968 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f2ba532cb29
RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000004
RBP: 00007f2ba52ec130 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f2ba52ec1c0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
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