[syzbot] [ext4?] UBSAN: shift-out-of-bounds in ext4_handle_clustersize

From: syzbot
Date: Thu Jun 22 2023 - 08:02:33 EST


Hello,

syzbot found the following issue on:

HEAD commit: 1b29d271614a Merge tag 'staging-6.4-rc7' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15fefd03280000
kernel config: https://syzkaller.appspot.com/x/.config?x=7ff8f87c7ab0e04e
dashboard link: https://syzkaller.appspot.com/bug?extid=f4cf49c6365d87eb8e0e
compiler: Debian clang version 15.0.7, 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/bd5aafc3a720/disk-1b29d271.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6689979a4ad9/vmlinux-1b29d271.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7f1acb11ce85/bzImage-1b29d271.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f4cf49c6365d87eb8e0e@xxxxxxxxxxxxxxxxxxxxxxxxx

UBSAN: shift-out-of-bounds in fs/ext4/super.c:4401:27
shift exponent 374 is too large for 32-bit type 'int'
CPU: 0 PID: 27421 Comm: syz-executor.0 Not tainted 6.4.0-rc6-syzkaller-00269-g1b29d271614a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
ubsan_epilogue lib/ubsan.c:217 [inline]
__ubsan_handle_shift_out_of_bounds+0x3c3/0x420 lib/ubsan.c:387
ext4_handle_clustersize+0x592/0x5c0 fs/ext4/super.c:4401
__ext4_fill_super fs/ext4/super.c:5279 [inline]
ext4_fill_super+0x3a66/0x6c60 fs/ext4/super.c:5672
get_tree_bdev+0x405/0x620 fs/super.c:1303
vfs_get_tree+0x8c/0x270 fs/super.c:1510
do_new_mount+0x28f/0xae0 fs/namespace.c:3039
do_mount fs/namespace.c:3382 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3568
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f7e1888d8ba
Code: 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d2 e8 b8 04 00 00 0f 1f 84 00 00 00 00 00 49 89 ca b8 a5 00 00 00 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:00007f7e195cef88 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 000000000000043c RCX: 00007f7e1888d8ba
RDX: 0000000020000440 RSI: 0000000020000180 RDI: 00007f7e195cefe0
RBP: 00007f7e195cf020 R08: 00007f7e195cf020 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020000440
R13: 0000000020000180 R14: 00007f7e195cefe0 R15: 00000000200001c0
</TASK>
================================================================================


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