[v6.1] UBSAN: array-index-out-of-bounds in xtLookup

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f2295faba5e8 Linux 6.1.88
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=101297bb180000
kernel config: https://syzkaller.appspot.com/x/.config?x=508163b9ab79dc25
dashboard link: https://syzkaller.appspot.com/bug?extid=d096957e6d0093838223
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/db6c44dd5d81/disk-f2295fab.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/96a1c7aa1507/vmlinux-f2295fab.xz
kernel image: https://storage.googleapis.com/syzbot-assets/84353702f58a/Image-f2295fab.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d09695...@syzkaller.appspotmail.com

================================================================================
UBSAN: array-index-out-of-bounds in fs/jfs/jfs_xtree.c:179:9
index 19 is out of range for type 'xad_t[18]' (aka 'struct xad[18]')
CPU: 1 PID: 5896 Comm: syz-executor.1 Not tainted 6.1.88-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call trace:
dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
dump_stack+0x1c/0x5c lib/dump_stack.c:113
ubsan_epilogue lib/ubsan.c:151 [inline]
__ubsan_handle_out_of_bounds+0xfc/0x148 lib/ubsan.c:282
xtLookup+0x70c/0x710 fs/jfs/jfs_xtree.c:179
extHint+0x200/0x544 fs/jfs/jfs_extent.c:215
jfs_get_block+0x2e4/0xb98 fs/jfs/inode.c:246
__block_write_begin_int+0x340/0x13b4 fs/buffer.c:1991
__block_write_begin fs/buffer.c:2041 [inline]
block_write_begin+0x98/0x11c fs/buffer.c:2102
jfs_write_begin+0x44/0x88 fs/jfs/inode.c:304
generic_perform_write+0x278/0x55c mm/filemap.c:3817
__generic_file_write_iter+0x168/0x388 mm/filemap.c:3945
generic_file_write_iter+0xb8/0x2b4 mm/filemap.c:3977
call_write_iter include/linux/fs.h:2265 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x610/0x914 fs/read_write.c:584
ksys_write+0x15c/0x26c fs/read_write.c:637
__do_sys_write fs/read_write.c:649 [inline]
__se_sys_write fs/read_write.c:646 [inline]
__arm64_sys_write+0x7c/0x90 fs/read_write.c:646
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
================================================================================


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