ntfs: Use ERR_CAST() to avoid cross-structure cast

When trying to propagate an error result, the error return path attempts
to retain the error, but does this with an open cast across very different
types, which the upcoming structure layout randomization plugin flags as
being potentially dangerous in the face of randomization. This is a false
positive, but what this code actually wants to do is use ERR_CAST() to
retain the error value.

Cc: Anton Altaparmakov <anton@tuxera.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/fs/ntfs/namei.c b/fs/ntfs/namei.c
index 358258364616cd3c2fee997daca2a192719cb045..4690cd75d8d7948a056fe899bc4600ade10b8566 100644 (file)
--- a/fs/ntfs/namei.c
+++ b/fs/ntfs/namei.c
@@ -159,7 +159,7 @@ static struct dentry *ntfs_lookup(struct inode *dir_ino, struct dentry *dent,
                                        PTR_ERR(dent_inode));
                kfree(name);
                /* Return the error code. */
-               return (struct dentry *)dent_inode;
+               return ERR_CAST(dent_inode);
        }
        /* It is guaranteed that @name is no longer allocated at this point. */
        if (MREF_ERR(mref) == -ENOENT) {