[PATCH 5.10 32/63] f2fs: fix shift-out-of-bounds in sanity_check_raw_super()

Greg Kroah-Hartman
2021-01-04T16:03:05Z

From: Chao Yu <yuchao0@huawei.com>

commit e584bbe821229a3e7cc409eecd51df66f9268c21 upstream.

syzbot reported a bug which could cause shift-out-of-bounds issue,
fix it.

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
sanity_check_raw_super fs/f2fs/super.c:2812 [inline]
read_raw_super_block fs/f2fs/super.c:3267 [inline]
f2fs_fill_super.cold+0x16c9/0x16f6 fs/f2fs/super.c:3519
mount_bdev+0x34d/0x410 fs/super.c:1366
legacy_get_tree+0x105/0x220 fs/fs_context.c:592
vfs_get_tree+0x89/0x2f0 fs/super.c:1496
do_new_mount fs/namespace.c:2896 [inline]
path_mount+0x12ae/0x1e70 fs/namespace.c:3227
do_mount fs/namespace.c:3240 [inline]
__do_sys_mount fs/namespace.c:3448 [inline]
__se_sys_mount fs/namespace.c:3425 [inline]
__x64_sys_mount+0x27f/0x300 fs/namespace.c:3425
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported-by: syzbot+ca9a785f8ac472085994@syzkaller.appspotmail.com
Signed-off-by: Anant Thazhemadam <anant.thazhemadam@gmail.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/f2fs/super.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2744,7 +2744,6 @@ static int sanity_check_raw_super(struct
block_t total_sections, blocks_per_seg;
struct f2fs_super_block *raw_super = (struct f2fs_super_block *)
(bh->b_data + F2FS_SUPER_OFFSET);
- unsigned int blocksize;
size_t crc_offset = 0;
__u32 crc = 0;

@@ -2778,10 +2777,10 @@ static int sanity_check_raw_super(struct
}

/* Currently, support only 4KB block size */
- blocksize = 1 << le32_to_cpu(raw_super->log_blocksize);
- if (blocksize != F2FS_BLKSIZE) {
- f2fs_info(sbi, "Invalid blocksize (%u), supports only 4KB",
- blocksize);
+ if (le32_to_cpu(raw_super->log_blocksize) != F2FS_BLKSIZE_BITS) {
+ f2fs_info(sbi, "Invalid log_blocksize (%u), supports only %u",
+ le32_to_cpu(raw_super->log_blocksize),
+ F2FS_BLKSIZE_BITS);
return -EFSCORRUPTED;
}