linux-kernel - Re: [syzbot] UBSAN: shift-out-of-bounds in init

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Message-ID: <00000000000042dafa05e8b911a6@google.com>
Date:   Thu, 15 Sep 2022 08:40:39 -0700
From:   syzbot <syzbot+dcf33a7aae997956fe06@...kaller.appspotmail.com>
To:     agruenba@...hat.com, anprice@...hat.com, cluster-devel@...hat.com,
        fgheet255t@...il.com, linux-kernel@...r.kernel.org,
        rpeterso@...hat.com, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] UBSAN: shift-out-of-bounds in init_sb (3)

syzbot has found a reproducer for the following issue on:

HEAD commit:    e47eb90a0a9a Add linux-next specific files for 20220901
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=14c90dbf080000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7933882276523081
dashboard link: https://syzkaller.appspot.com/bug?extid=dcf33a7aae997956fe06
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=179ef880880000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17047887080000

Downloadable assets:
disk image: https://storage.googleapis.com/d3bf639370bc/disk-e47eb90a.raw.xz
vmlinux: https://storage.googleapis.com/1c9c27c6eeef/vmlinux-e47eb90a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+dcf33a7aae997956fe06@...kaller.appspotmail.com

loop0: detected capacity change from 0 to 256
gfs2: fsid=loop0: Trying to join cluster "lock_nolock", "loop0"
gfs2: fsid=loop0: Now mounting FS (format 1801)...
================================================================================
UBSAN: shift-out-of-bounds in fs/gfs2/ops_fstype.c:295:19
shift exponent 327683 is too large for 64-bit type 'long unsigned int'
CPU: 0 PID: 3611 Comm: syz-executor306 Not tainted 6.0.0-rc3-next-20220901-syzkaller #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
 gfs2_read_sb fs/gfs2/ops_fstype.c:295 [inline]
 init_sb.cold+0x19/0x109 fs/gfs2/ops_fstype.c:487
 gfs2_fill_super+0x17fe/0x27a0 fs/gfs2/ops_fstype.c:1209
 get_tree_bdev+0x440/0x760 fs/super.c:1323
 gfs2_get_tree+0x4a/0x270 fs/gfs2/ops_fstype.c:1325
 vfs_get_tree+0x89/0x2f0 fs/super.c:1530
 do_new_mount fs/namespace.c:3040 [inline]
 path_mount+0x1326/0x1e20 fs/namespace.c:3370
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount fs/namespace.c:3568 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568
 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: 0033:0x7fd9bd10d16a
Code: 83 c4 08 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 00 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:00007ffcd1985f38 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffcd1985f90 RCX: 00007fd9bd10d16a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffcd1985f50
RBP: 00007ffcd1985f50 R08: 00007ffcd1985f90 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000282 R12: 0000000020000218
R13: 0000000000000003 R14: 0000000000000004 R15: 0000000000000001
 </TASK>
================================================================================