Re: [syzbot] UBSAN: shift-out-of-bounds in jfs_open

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    3800a713b607 Merge tag 'mm-hotfixes-stable-2022-09-26' of ..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1073ecd4880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ba0d23aa7e1ffaf5
dashboard link: https://syzkaller.appspot.com/bug?extid=027aa1f5f8487ba60a97
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=103ceaa8880000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=125bd024880000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+027aa1f5f8487ba60a97@xxxxxxxxxxxxxxxxxxxxxxxxx

================================================================================
UBSAN: shift-out-of-bounds in fs/jfs/file.c:65:20
shift exponent 8205 is too large for 64-bit type '__u64' (aka 'unsigned long long')
CPU: 1 PID: 3690 Comm: syz-executor342 Not tainted 6.0.0-rc7-syzkaller-00029-g3800a713b607 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
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_shift_out_of_bounds+0x33d/0x3b0 lib/ubsan.c:322
 jfs_open+0x3a2/0x3d0 fs/jfs/file.c:65
 do_dentry_open+0x777/0x1180 fs/open.c:880
 do_open fs/namei.c:3557 [inline]
 path_openat+0x25fc/0x2df0 fs/namei.c:3691
 do_filp_open+0x264/0x4f0 fs/namei.c:3718
 do_sys_openat2+0x124/0x4e0 fs/open.c:1313
 do_sys_open fs/open.c:1329 [inline]
 __do_sys_openat fs/open.c:1345 [inline]
 __se_sys_openat fs/open.c:1340 [inline]
 __x64_sys_openat+0x243/0x290 fs/open.c:1340
 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: 0033:0x7f2044cd6ed9
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:00007f2044c4c278 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f2044d624b0 RCX: 00007f2044cd6ed9
RDX: 0000000000161842 RSI: 000000002000c380 RDI: 00000000ffffff9c
RBP: 00007f2044d2de4c R08: 00007f2044c4c700 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f2044d29108
R13: 0030656c69662f2e R14: 00007f2044c4c400 R15: 00007f2044d624b8
 </TASK>
================================================================================