[PATCH 4.5 165/200] ext4/fscrypto: avoid RCU lookup in d_revalidate

Greg Kroah-Hartman
2016-05-03T01:00:47Z

From: Jaegeuk Kim <jaegeuk@kernel.org>

commit 03a8bb0e53d9562276045bdfcf2b5de2e4cff5a1 upstream.

As Al pointed, d_revalidate should return RCU lookup before using d_inode.
This was originally introduced by:
commit 34286d666230 ("fs: rcu-walk aware d_revalidate method").

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ext4/crypto.c | 4 ++++
1 file changed, 4 insertions(+)

--- a/fs/ext4/crypto.c
+++ b/fs/ext4/crypto.c
@@ -34,6 +34,7 @@
#include <linux/random.h>
#include <linux/scatterlist.h>
#include <linux/spinlock_types.h>
+#include <linux/namei.h>

#include "ext4_extents.h"
#include "xattr.h"
@@ -479,6 +480,9 @@ static int ext4_d_revalidate(struct dent
struct ext4_crypt_info *ci;
int dir_has_key, cached_with_key;

+ if (flags & LOOKUP_RCU)
+ return -ECHILD;
+
dir = dget_parent(dentry);
if (!ext4_encrypted_inode(d_inode(dir))) {
dput(dir);