UBSAN: shift-out-of-bounds in erofs_fc_fill_super

syzbot syzbot+c68f467cd7c45860e8d4 at
Wed Jan 20 04:38:17 AEDT 2021


syzbot found the following issue on:

HEAD commit:    b3a3cbde Add linux-next specific files for 20210115
git tree:       linux-next
console output:
kernel config:
dashboard link:
compiler:       gcc (GCC) 10.1.0-syz 20200507
syz repro:
C reproducer:

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c68f467cd7c45860e8d4 at

loop0: detected capacity change from 4 to 0
UBSAN: shift-out-of-bounds in fs/erofs/super.c:161:3
shift exponent 59 is too large for 32-bit type 'int'
CPU: 1 PID: 8462 Comm: syz-executor591 Not tainted 5.11.0-rc3-next-20210115-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 ubsan_epilogue+0xb/0x5a lib/ubsan.c:148
 __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:395
 erofs_read_superblock fs/erofs/super.c:161 [inline]
 erofs_fc_fill_super.cold+0x6c/0x35c fs/erofs/super.c:357
 get_tree_bdev+0x440/0x760 fs/super.c:1291
 vfs_get_tree+0x89/0x2f0 fs/super.c:1496
 do_new_mount fs/namespace.c:2889 [inline]
 path_mount+0x12ae/0x1e70 fs/namespace.c:3220
 do_mount fs/namespace.c:3233 [inline]
 __do_sys_mount fs/namespace.c:3441 [inline]
 __se_sys_mount fs/namespace.c:3418 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3418
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
RIP: 0033:0x446d1a
Code: b8 08 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 fd ad fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 da ad fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007fff68419868 EFLAGS: 00000297 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fff684198c0 RCX: 0000000000446d1a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007fff68419880
RBP: 00007fff68419880 R08: 00007fff684198c0 R09: 00007fff00000015
R10: 0000000000000000 R11: 0000000000000297 R12: 0000000000000001
R13: 0000000000000004 R14: 0000000000000003 R15: 0000000000000003

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