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

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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    0a924817d2ed Merge tag '6.2-rc-smb3-client-fixes-part2' of..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=161140ff880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4e2d7bfa2d6d5a76
dashboard link: https://syzkaller.appspot.com/bug?extid=853a6f4dfa3cf37d3aea
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=14eedba0480000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13760874480000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b0959a409a79/disk-0a924817.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/388daa76797b/vmlinux-0a924817.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b9d2d406c075/bzImage-0a924817.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/c5bcb129d7ea/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+853a6f4dfa3cf37d3aea@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 32768
================================================================================
UBSAN: array-index-out-of-bounds in fs/jfs/jfs_dmap.c:1964:6
index -84 is out of range for type 's8 [341]'
CPU: 1 PID: 5074 Comm: syz-executor352 Not tainted 6.1.0-syzkaller-14321-g0a924817d2ed #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
 dbAllocDmapLev+0x3c6/0x420 fs/jfs/jfs_dmap.c:1964
 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_create+0x736/0xb10 fs/jfs/namei.c:137
 lookup_open fs/namei.c:3413 [inline]
 open_last_lookups fs/namei.c:3481 [inline]
 path_openat+0x12ac/0x2dd0 fs/namei.c:3711
 do_filp_open+0x264/0x4f0 fs/namei.c:3741
 do_sys_openat2+0x124/0x4e0 fs/open.c:1310
 do_sys_open fs/open.c:1326 [inline]
 __do_sys_openat fs/open.c:1342 [inline]
 __se_sys_openat fs/open.c:1337 [inline]
 __x64_sys_openat+0x243/0x290 fs/open.c:1337
 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: 0033:0x7fe62a3507c9
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:00007ffe095987c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe62a3507c9
RDX: 000000000000275a RSI: 0000000020000040 RDI: 00000000ffffff9c
RBP: 00007fe62a310060 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe62a3100f0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
================================================================================


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