[PATCH] eCryptfs: ecryptfs_setattr() bugfix

[Michael Halcrow <mhalcrow@us.ibm.com>]

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>
---
 fs/ecryptfs/inode.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 83e94fe..9c6877c 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;
-- 
1.5.2.1