Revert "f2fs: avoid out-of-range memory access"

[ Upstream commit a37d0862d17411edb67677a580a6f505ec2225f6 ]

As Pavel Machek reported:

"We normally use -EUCLEAN to signal filesystem corruption. Plus, it is
good idea to report it to the syslog and mark filesystem as "needing
fsck" if filesystem can do that."

Still we need improve the original patch with:
- use unlikely keyword
- add message print
- return EUCLEAN

However, after rethink this patch, I don't think we should add such
condition check here as below reasons:
- We have already checked the field in f2fs_sanity_check_ckpt(),
- If there is fs corrupt or security vulnerability, there is nothing
to guarantee the field is integrated after the check, unless we do
the check before each of its use, however no filesystem does that.
- We only have similar check for bitmap, which was added due to there
is bitmap corruption happened on f2fs' runtime in product.
- There are so many key fields in SB/CP/NAT did have such check
after f2fs_sanity_check_{sb,cp,..}.

So I propose to revert this unneeded check.

This reverts commit 56f3ce675103e3fb9e631cfb4131fc768bc23e9a.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>

fs/f2fs/segment.c

@@ -3261,11 +3261,6 @@ static int read_compacted_summaries(struct f2fs_sb_info *sbi)
 		seg_i = CURSEG_I(sbi, i);
 		segno = le32_to_cpu(ckpt->cur_data_segno[i]);
 		blk_off = le16_to_cpu(ckpt->cur_data_blkoff[i]);
-		if (blk_off > ENTRIES_IN_SUM) {
-			f2fs_bug_on(sbi, 1);
-			f2fs_put_page(page, 1);
-			return -EFAULT;
-		}
 		seg_i->next_segno = segno;
 		reset_curseg(sbi, i, 0);
 		seg_i->alloc_type = ckpt->alloc_type[i];