[syzbot] UBSAN: array-index-out-of-bounds in xtLookup

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    b229b6ca5abb Merge tag 'perf-tools-fixes-for-v6.1-2022-10-..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=144f6876880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1d3548a4365ba17d
dashboard link: https://syzkaller.appspot.com/bug?extid=e526b0844b096abaa8c7
compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/24728b72a896/disk-b229b6ca.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/10a3c40c60e1/vmlinux-b229b6ca.xz
kernel image: https://storage.googleapis.com/syzbot-assets/69f963b02b7e/bzImage-b229b6ca.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e526b0844b096abaa8c7@xxxxxxxxxxxxxxxxxxxxxxxxx

================================================================================
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]'
CPU: 1 PID: 8948 Comm: syz-executor.1 Not tainted 6.1.0-rc2-syzkaller-00105-gb229b6ca5abb #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106
 ubsan_epilogue lib/ubsan.c:151 [inline]
 __ubsan_handle_out_of_bounds+0xdb/0x130 lib/ubsan.c:283
 xtLookup+0x86c/0x880 fs/jfs/jfs_xtree.c:179
 jfs_get_block+0x24b/0xce0 fs/jfs/inode.c:218
 do_mpage_readpage+0x970/0x1c50 fs/mpage.c:208
 mpage_readahead+0x210/0x380 fs/mpage.c:361
 read_pages+0x169/0x9c0 mm/readahead.c:161
 page_cache_ra_unbounded+0x703/0x820 mm/readahead.c:270
 filemap_readahead mm/filemap.c:2557 [inline]
 filemap_get_pages+0x72f/0x10d0 mm/filemap.c:2597
 filemap_read+0x3cf/0xea0 mm/filemap.c:2675
 call_read_iter include/linux/fs.h:2185 [inline]
 generic_file_splice_read+0x1ff/0x5d0 fs/splice.c:309
 do_splice_to fs/splice.c:793 [inline]
 splice_direct_to_actor+0x41b/0xc00 fs/splice.c:865
 do_splice_direct+0x279/0x3d0 fs/splice.c:974
 do_sendfile+0x5fb/0xf80 fs/read_write.c:1255
 __do_sys_sendfile64 fs/read_write.c:1323 [inline]
 __se_sys_sendfile64+0x14f/0x1b0 fs/read_write.c:1309
 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: 0033:0x7f59e548b5a9
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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f59e6216168 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f59e55abf80 RCX: 00007f59e548b5a9
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 0000000000000008
RBP: 00007f59e54e67b0 R08: 0000000000000000 R09: 0000000000000000
R10: 0001000000201005 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff7e17c23f R14: 00007f59e6216300 R15: 0000000000022000
 </TASK>
================================================================================


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