reiserfs: preserve i_mode if __reiserfs_set_acl() fails

When changing a file's acl mask, reiserfs_set_acl() will first set the
group bits of i_mode to the value of the mask, and only then set the
actual extended attribute representing the new acl.

If the second part fails (due to lack of space, for example) and the
file had no acl attribute to begin with, the system will from now on
assume that the mask permission bits are actual group permission bits,
potentially granting access to the wrong users.

Prevent this by only changing the inode mode after the acl has been set.
Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/reiserfs/xattr_acl.c

@@ -23,7 +23,8 @@ reiserfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 	struct reiserfs_transaction_handle th;
 	size_t jcreate_blocks;
 	int size = acl ? posix_acl_xattr_size(acl->a_count) : 0;
-
+	int update_mode = 0;
+	umode_t mode = inode->i_mode;
 
 	/*
 	 * Pessimism: We can't assume that anything from the xattr root up
@@ -38,12 +39,14 @@ reiserfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 	reiserfs_write_unlock(inode->i_sb);
 	if (error == 0) {
 		if (type == ACL_TYPE_ACCESS && acl) {
-			error = posix_acl_update_mode(inode, &inode->i_mode,
-						      &acl);
+			error = posix_acl_update_mode(inode, &mode, &acl);
 			if (error)
 				goto unlock;
+			update_mode = 1;
 		}
 		error = __reiserfs_set_acl(&th, inode, type, acl);
+		if (!error && update_mode)
+			inode->i_mode = mode;
 unlock:
 		reiserfs_write_lock(inode->i_sb);
 		error2 = journal_end(&th);