Btrfs: deal with NULL acl sent to btrfs_set_acl

It is legal for btrfs_set_acl to be sent a NULL acl.  This
makes sure we don't dereference it.  A similar patch was sent by
Johannes Hirte <johannes.hirte@fem.tu-ilmenau.de>

Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/acl.c b/fs/btrfs/acl.c
index 1898f8555f06cf3284bd9f7317cb75618b97ab53..fa44e92e9b8fa437c6d18fc4643fdbc66bde7905 100644 (file)
--- a/fs/btrfs/acl.c
+++ b/fs/btrfs/acl.c
@@ -112,12 +112,14 @@ static int btrfs_set_acl(struct btrfs_trans_handle *trans,
        switch (type) {
        case ACL_TYPE_ACCESS:
                mode = inode->i_mode;
-               ret = posix_acl_equiv_mode(acl, &mode);
-               if (ret < 0)
-                       return ret;
-               ret = 0;
-               inode->i_mode = mode;
                name = POSIX_ACL_XATTR_ACCESS;
+               if (acl) {
+                       ret = posix_acl_equiv_mode(acl, &mode);
+                       if (ret < 0)
+                               return ret;
+                       inode->i_mode = mode;
+               }
+               ret = 0;
                break;
        case ACL_TYPE_DEFAULT:
                if (!S_ISDIR(inode->i_mode))