[lvc-project] [PATCH] ocfs2: add directory size check to ocfs2_find_dir_space_id()

[Dmitry Antipov]

In 'ocfs2_find_dir_space_id()', add extra check whether the directory
data block is large enough to hold at least one directory entry, and
raise 'ocfs2_error()' if the former is unexpectedly small.

Reported-by: syzbot+ded9116588a7b73c34bc at syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=ded9116588a7b73c34bc
Signed-off-by: Dmitry Antipov <dmantipov at yandex.ru>
---
 fs/ocfs2/dir.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c
index b9bf1428a3d9..3c2dacba9b0a 100644
--- a/fs/ocfs2/dir.c
+++ b/fs/ocfs2/dir.c
@@ -3444,6 +3444,14 @@ static int ocfs2_find_dir_space_id(struct inode *dir, struct buffer_head *di_bh,
 		offset += le16_to_cpu(de->rec_len);
 	}
 
+	if (!last_de) {
+		ret = ocfs2_error(sb, "Directory entry (#%llu: size=%lld) "
+				  "is unexpectedly short",
+				  (unsigned long long)OCFS2_I(dir)->ip_blkno,
+				  i_size_read(dir));
+		goto out;
+	}
+
 	/*
 	 * We're going to require expansion of the directory - figure
 	 * out how many blocks we'll need so that a place for the
-- 
2.51.0