[PATCH 4.5 162/200] f2fs crypto: fix corrupted symlink in encrypted case

[Greg Kroah-Hartman]

4.5-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>

commit c90e09f7fb498f81cd4e8bb6460d3a26ccebeca3 upstream.

In the encrypted symlink case, we should check its corrupted symname after
decrypting it.
Otherwise, we can report -ENOENT incorrectly, if encrypted symname starts with
'\0'.

Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/f2fs/namei.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -980,12 +980,6 @@ static const char *f2fs_encrypted_get_li
 	}
 	memcpy(cstr.name, sd->encrypted_path, cstr.len);
 
-	/* this is broken symlink case */
-	if (unlikely(cstr.name[0] == 0)) {
-		res = -ENOENT;
-		goto errout;
-	}
-
 	if ((cstr.len + sizeof(struct f2fs_encrypted_symlink_data) - 1) >
 								max_size) {
 		/* Symlink data on the disk is corrupted */
@@ -1002,6 +996,12 @@ static const char *f2fs_encrypted_get_li
 
 	kfree(cstr.name);
 
+	/* this is broken symlink case */
+	if (unlikely(pstr.name[0] == 0)) {
+		res = -ENOENT;
+		goto errout;
+	}
+
 	paddr = pstr.name;
 
 	/* Null-terminate the name */