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

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    72a85e2b0a1e Merge tag 'spi-fix-v6.2-rc1' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16d22974480000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4e2d7bfa2d6d5a76
dashboard link: https://syzkaller.appspot.com/bug?extid=76a072c2f8a60280bd70
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=15802088480000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/510d16df06c8/disk-72a85e2b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/50ef5477a1d4/vmlinux-72a85e2b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f2acd6f1189a/bzImage-72a85e2b.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/5e378294b8d6/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+76a072c2f8a60280bd70@xxxxxxxxxxxxxxxxxxxxxxxxx

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UBSAN: array-index-out-of-bounds in fs/jfs/jfs_xtree.c:360:4
index 19 is out of range for type 'xad_t [18]'
CPU: 1 PID: 5414 Comm: syz-executor.0 Not tainted 6.1.0-syzkaller-14594-g72a85e2b0a1e #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
 xtSearch+0x709/0x1cb0 fs/jfs/jfs_xtree.c:360
 xtLookup+0x235/0x880 fs/jfs/jfs_xtree.c:152
 extHint+0x204/0x630 fs/jfs/jfs_extent.c:215
 jfs_get_block+0x2e3/0xce0 fs/jfs/inode.c:246
 get_more_blocks fs/direct-io.c:665 [inline]
 do_direct_IO fs/direct-io.c:953 [inline]
 __blockdev_direct_IO+0x1737/0x3bf0 fs/direct-io.c:1266
 blockdev_direct_IO include/linux/fs.h:3213 [inline]
 jfs_direct_IO+0xf6/0x1e0 fs/jfs/inode.c:331
 generic_file_direct_write+0x294/0x610 mm/filemap.c:3696
 __generic_file_write_iter+0x1c4/0x400 mm/filemap.c:3856
 generic_file_write_iter+0xab/0x310 mm/filemap.c:3932
 do_iter_write+0x6c2/0xc20 fs/read_write.c:861
 iter_file_splice_write+0x7fc/0xfc0 fs/splice.c:686
 do_splice_from fs/splice.c:764 [inline]
 direct_splice_actor+0xe6/0x1c0 fs/splice.c:931
 splice_direct_to_actor+0x4e4/0xc00 fs/splice.c:886
 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: 0033:0x7f9065c8c0a9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 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:00007f90669ab168 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f9065dac050 RCX: 00007f9065c8c0a9
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000007
RBP: 00007f9065ce7ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 000080001d00c0d0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe07df477f R14: 00007f90669ab300 R15: 0000000000022000
 </TASK>
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