From 81e366f87f52c62671fb1d8050572e68dbcf1d22 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Thu, 10 Jul 2014 12:37:46 +0800 Subject: [PATCH] f2fs: check name_len of dir entry to prevent from deadloop We assume that modification of some special application could result in zeroed name_len, or it is consciously made by somebody. We will deadloop in find_in_block when name_len of dir entry is zero. This patch is added for preventing deadloop in above scenario. change log from v1: o use f2fs_bug_on rather than break out from searching dir entry suggested by Jaegeuk Kim. Jaegeuk describe: "Well, IMO, it would be good to add f2fs_bug_on() here with a specific comment. In the current phase of f2fs, it is more important to investigate the file system bugs, rather than workarounds for any corrupted images. And, definitely it needs to stop the kernel if any corrupted image was mounted, so that we can figure out where the bugs are occurred." Suggested-by: Jaegeuk Kim Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/dir.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c index e84e8807c651..bcf893c3d903 100644 --- a/fs/f2fs/dir.c +++ b/fs/f2fs/dir.c @@ -121,6 +121,13 @@ static struct f2fs_dir_entry *find_in_block(struct page *dentry_page, *max_slots = max_len; max_len = 0; } + + /* + * For the most part, it should be a bug when name_len is zero. + * We stop here for figuring out where the bugs are occurred. + */ + f2fs_bug_on(!de->name_len); + bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len)); } -- 2.30.2