linux-kernel - [syzbot] [ext4?] UBSAN: shift-out-of-bounds in ext2_fill

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Date:   Fri, 24 Feb 2023 11:48:42 -0800
From:   syzbot <syzbot+4fec412f59eba8c01b77@...kaller.appspotmail.com>
To:     jack@...e.com, linux-ext4@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: [syzbot] [ext4?] UBSAN: shift-out-of-bounds in ext2_fill_super

Hello,

syzbot found the following issue on:

HEAD commit:    a9b06ec42c0f Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=1646c5e8c80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8ad40c5d31656db1
dashboard link: https://syzkaller.appspot.com/bug?extid=4fec412f59eba8c01b77
compiler:       Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=172f9f58c80000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13607dcf480000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3fd9d14dbef6/disk-a9b06ec4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d4fd6fe60f78/vmlinux-a9b06ec4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/908925a4e5fc/Image-a9b06ec4.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/322d1cd45d78/mount_1.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4fec412f59eba8c01b77@...kaller.appspotmail.com

loop0: detected capacity change from 0 to 512
================================================================================
UBSAN: shift-out-of-bounds in fs/ext2/super.c:948:25
shift exponent 32 is too large for 32-bit type 'int'
CPU: 1 PID: 5922 Comm: syz-executor396 Not tainted 6.2.0-syzkaller-18295-ga9b06ec42c0f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/21/2023
Call trace:
 dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106
 dump_stack+0x1c/0x28 lib/dump_stack.c:113
 ubsan_epilogue lib/ubsan.c:151 [inline]
 __ubsan_handle_shift_out_of_bounds+0x2f4/0x36c lib/ubsan.c:321
 ext2_fill_super+0x2074/0x23fc fs/ext2/super.c:948
 mount_bdev+0x26c/0x368 fs/super.c:1359
 ext2_mount+0x44/0x58 fs/ext2/super.c:1484
 legacy_get_tree+0xd4/0x16c fs/fs_context.c:610
 vfs_get_tree+0x90/0x274 fs/super.c:1489
 do_new_mount+0x25c/0x8c8 fs/namespace.c:3145
 path_mount+0x590/0xe58 fs/namespace.c:3475
 do_mount fs/namespace.c:3488 [inline]
 __do_sys_mount fs/namespace.c:3697 [inline]
 __se_sys_mount fs/namespace.c:3674 [inline]
 __arm64_sys_mount+0x45c/0x594 fs/namespace.c:3674
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591
================================================================================
EXT2-fs (loop0): error: fragsize 4096 != blocksize 1024(not supported yet)


---
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