ecryptfs: fix failure handling in ->readlink()

If ecryptfs_readlink_lower() fails, buf remains an uninitialized
pointer and passing it nd_set_link() won't do anything good.

Fixed by switching ecryptfs_readlink_lower() to saner API - make it
return buf or ERR_PTR(...) and update callers.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index c36c4482447159c219a4d4f56506087229ebb276..b167ca48b8eef4984dec79a609644012421e6fea 100644 (file)
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -659,19 +659,17 @@ out_lock:
        return rc;
 }
 
-static int ecryptfs_readlink_lower(struct dentry *dentry, char **buf,
-                                  size_t *bufsiz)
+static char *ecryptfs_readlink_lower(struct dentry *dentry, size_t *bufsiz)
 {
        struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
        char *lower_buf;
+       char *buf;
        mm_segment_t old_fs;
        int rc;
 
        lower_buf = kmalloc(PATH_MAX, GFP_KERNEL);
-       if (!lower_buf) {
-               rc = -ENOMEM;
-               goto out;
-       }
+       if (!lower_buf)
+               return ERR_PTR(-ENOMEM);
        old_fs = get_fs();
        set_fs(get_ds());
        rc = lower_dentry->d_inode->i_op->readlink(lower_dentry,
@@ -680,21 +678,18 @@ static int ecryptfs_readlink_lower(struct dentry *dentry, char **buf,
        set_fs(old_fs);
        if (rc < 0)
                goto out;
-       rc = ecryptfs_decode_and_decrypt_filename(buf, bufsiz, dentry->d_sb,
+       rc = ecryptfs_decode_and_decrypt_filename(&buf, bufsiz, dentry->d_sb,
                                                  lower_buf, rc);
 out:
        kfree(lower_buf);
-       return rc;
+       return rc ? ERR_PTR(rc) : buf;
 }
 
 static void *ecryptfs_follow_link(struct dentry *dentry, struct nameidata *nd)
 {
-       char *buf;
-       size_t len = PATH_MAX;
-       int rc;
-
-       rc = ecryptfs_readlink_lower(dentry, &buf, &len);
-       if (rc)
+       size_t len;
+       char *buf = ecryptfs_readlink_lower(dentry, &len);
+       if (IS_ERR(buf))
                goto out;
        fsstack_copy_attr_atime(dentry->d_inode,
                                ecryptfs_dentry_to_lower(dentry)->d_inode);
@@ -1003,10 +998,12 @@ static int ecryptfs_getattr_link(struct vfsmount *mnt, struct dentry *dentry,
                char *target;
                size_t targetsiz;
 
-               rc = ecryptfs_readlink_lower(dentry, &target, &targetsiz);
-               if (!rc) {
+               target = ecryptfs_readlink_lower(dentry, &targetsiz);
+               if (!IS_ERR(target)) {
                        kfree(target);
                        stat->size = targetsiz;
+               } else {
+                       rc = PTR_ERR(target);
                }
        }
        return rc;