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

[syzbot <syzbot+75c177aa1291e7fe423d@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    f67dd6ce0723 Merge tag 'slab-for-6.1-rc4-fixes' of git://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=102b0615880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=771b06c41e08f95b
dashboard link: https://syzkaller.appspot.com/bug?extid=75c177aa1291e7fe423d
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/0ddcda4f997e/disk-f67dd6ce.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ced709971cf5/vmlinux-f67dd6ce.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d35fb69a1976/bzImage-f67dd6ce.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+75c177aa1291e7fe423d@syzkaller.appspotmail.com

================================================================================
UBSAN: array-index-out-of-bounds in fs/jfs/jfs_xtree.c:2304:9
index 19 is out of range for type 'xad_t [18]'
CPU: 0 PID: 4605 Comm: syz-executor.4 Not tainted 6.1.0-rc4-syzkaller-00020-gf67dd6ce0723 #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+0x1b1/0x28e lib/dump_stack.c:106
 ubsan_epilogue lib/ubsan.c:151 [inline]
 __ubsan_handle_out_of_bounds+0xdb/0x130 lib/ubsan.c:283
 xtTruncate+0x2778/0x32d0 fs/jfs/jfs_xtree.c:2304
 jfs_truncate_nolock+0x192/0x390 fs/jfs/inode.c:393
 jfs_truncate+0xc6/0x140 fs/jfs/inode.c:417
 jfs_direct_IO+0x1b0/0x1e0 fs/jfs/inode.c:347
 generic_file_direct_write+0x294/0x610 mm/filemap.c:3677
 __generic_file_write_iter+0x1c4/0x400 mm/filemap.c:3837
 generic_file_write_iter+0xab/0x310 mm/filemap.c:3913
 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: 0033:0x7f22df88b639
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:00007f22e0602168 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f22df9abf80 RCX: 00007f22df88b639
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000003
RBP: 00007f22df8e67e1 R08: 0000000000000000 R09: 0000000000000000
R10: 000080001d00c0d0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc01280fbf R14: 00007f22e0602300 R15: 0000000000022000
 </TASK>
================================================================================


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