eCryptfs: ecryptfs_setattr() bugfix

There is another bug recently introduced into the ecryptfs_setattr()
function in 2.6.22.  eCryptfs will attempt to treat special files like
regular eCryptfs files on chmod, chown, and so forth.  This leads to a NULL
pointer dereference.  This patch validates that the file is a regular file
before proceeding with operations related to the inode's crypt_stat.

Thanks to Ryusuke Konishi for finding this bug and suggesting the fix.

Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index e77a2ec71aa5..0a50942b4378 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -902,8 +902,9 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
         mutex_lock(&crypt_stat->cs_mutex);
         if (S_ISDIR(dentry->d_inode->i_mode))
                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
-        else if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
-                 || !(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
+        else if (S_ISREG(dentry->d_inode->i_mode)
+                 && (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
+                     || !(crypt_stat->flags & ECRYPTFS_KEY_VALID))) {
                 struct vfsmount *lower_mnt;
                 struct file *lower_file = NULL;
                 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;