[v5.15] UBSAN: array-index-out-of-bounds in xtLookup

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4af60700a60c Linux 5.15.119
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15c764a4a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=4ea969bb1404ea8d
dashboard link: https://syzkaller.appspot.com/bug?extid=de1c7786b6353c986da5
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=151167eca80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10e4054f280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1e0ea32bdd98/disk-4af60700.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cb01185787c3/vmlinux-4af60700.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8f7a5f7e0bc5/bzImage-4af60700.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/75a12a544bd8/mount_0.gz
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/2be9f8229121/mount_8.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+de1c77...@syzkaller.appspotmail.com

================================================================================
UBSAN: array-index-out-of-bounds in fs/jfs/jfs_xtree.c:190:9
index 19 is out of range for type 'xad_t[18]' (aka 'struct xad[18]')
CPU: 1 PID: 4121 Comm: syz-executor408 Not tainted 5.15.119-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
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_out_of_bounds+0x118/0x140 lib/ubsan.c:282
xtLookup+0x8cc/0x8e0 fs/jfs/jfs_xtree.c:190
jfs_get_block+0x2e5/0xe50 fs/jfs/inode.c:218
get_more_blocks fs/direct-io.c:673 [inline]
do_direct_IO fs/direct-io.c:959 [inline]
do_blockdev_direct_IO fs/direct-io.c:1276 [inline]
__blockdev_direct_IO+0x1b13/0x4f40 fs/direct-io.c:1368
blockdev_direct_IO include/linux/fs.h:3230 [inline]
jfs_direct_IO+0xf6/0x1e0 fs/jfs/inode.c:343
generic_file_direct_write+0x204/0x460 mm/filemap.c:3678
__generic_file_write_iter+0x2a2/0x4f0 mm/filemap.c:3860
generic_file_write_iter+0xa7/0x1b0 mm/filemap.c:3935
do_iter_readv_writev+0x594/0x7a0
do_iter_write+0x1ea/0x760 fs/read_write.c:855
iter_file_splice_write+0x806/0xfa0 fs/splice.c:689
do_splice_from fs/splice.c:767 [inline]
direct_splice_actor+0xe3/0x1c0 fs/splice.c:936
splice_direct_to_actor+0x500/0xc10 fs/splice.c:891
do_splice_direct+0x285/0x3d0 fs/splice.c:979
do_sendfile+0x625/0xff0 fs/read_write.c:1249
__do_sys_sendfile64 fs/read_write.c:1317 [inline]
__se_sys_sendfile64+0x178/0x1e0 fs/read_write.c:1303
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+0x61/0xcb
RIP: 0033:0x7f8a10ca9f09
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 a1 15 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:00007f8a10c542f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f8a10d547e0 RCX: 00007f8a10ca9f09
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000008
RBP: 00007f8a10d547ec R08: 0000000000000000 R09: 0000000000000000
R10: 0001000000201004 R11: 0000000000000246 R12: 00007f8a10d20ed0
R13: 723d73726f727265 R14: 0030656c69662f2e R15: 00007f8a10d547e8
</TASK>
================================================================================


---
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