ext4/fscrypto: avoid RCU lookup in d_revalidate

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: Eric Biggers <ebiggers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
index 1259ade2f10a2c6df3d174047bbf3cb04fce34f5..9d6c2dcf1bd055fa37db1946f8366d8240703e4b 100644 (file)
--- 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"
@@ -481,6 +482,9 @@ static int ext4_d_revalidate(struct dentry *dentry, unsigned int flags)
        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);