[syzbot] UBSAN: shift-out-of-bounds in extAlloc

[syzbot] UBSAN: shift-out-of-bounds in extAlloc

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    105a36f3694e Merge tag 'kbuild-fixes-v6.0-3' of git://git...
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=14b56188880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=122d7bd4fc8e0ecb
dashboard link: https://syzkaller.appspot.com/bug?extid=5f088f29593e6b4c8db8
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14735cdf080000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15dfcdc4880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d3172aeebe38/disk-105a36f3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/75046f57bda3/vmlinux-105a36f3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5f088f29593e6b4c8db8@syzkaller.appspotmail.com

================================================================================
UBSAN: shift-out-of-bounds in fs/jfs/jfs_extent.c:314:16
shift exponent -1 is negative
CPU: 0 PID: 3605 Comm: syz-executor226 Not tainted 6.0.0-rc6-syzkaller-00321-g105a36f3694e #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+0xcd/0x134 lib/dump_stack.c:106
 ubsan_epilogue+0xb/0x50 lib/ubsan.c:151
 __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x187 lib/ubsan.c:322
 extBalloc fs/jfs/jfs_extent.c:314 [inline]
 extAlloc.cold+0x8d/0x92 fs/jfs/jfs_extent.c:122
 jfs_get_block+0x661/0xa90 fs/jfs/inode.c:248
 __block_write_begin_int+0x3ca/0x1520 fs/buffer.c:2006
 __block_write_begin fs/buffer.c:2056 [inline]
 block_write_begin+0xb5/0x4d0 fs/buffer.c:2117
 jfs_write_begin+0x2d/0xd0 fs/jfs/inode.c:304
 generic_perform_write+0x246/0x560 mm/filemap.c:3738
 __generic_file_write_iter+0x2aa/0x4d0 mm/filemap.c:3866
 generic_file_write_iter+0xdf/0x350 mm/filemap.c:3898
 call_write_iter include/linux/fs.h:2187 [inline]
 do_iter_readv_writev+0x20b/0x3b0 fs/read_write.c:729
 do_iter_write+0x182/0x700 fs/read_write.c:855
 vfs_writev+0x1aa/0x630 fs/read_write.c:928
 do_writev+0x133/0x2f0 fs/read_write.c:971
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f61f4034f29
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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd1287f7a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 0000000000000016 RCX: 00007f61f4034f29
RDX: 0000000000000001 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 00007f61f3ff46f0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000f8008000
R13: 0000000000000000 R14: 00080000000000f8 R15: 0000000000000000
 </TASK>
================================================================================


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