Prevent oopsing in posix_acl_valid()

If posix_acl_from_xattr() returns an error code, a negative address is
dereferenced causing an oops; fix by checking for error code first.

Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Reviewed-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/fs/btrfs/acl.c b/fs/btrfs/acl.c
index a892bc27f13a..827be9a6ca33 100644
--- a/fs/btrfs/acl.c
+++ b/fs/btrfs/acl.c
@@ -178,12 +178,13 @@ static int btrfs_xattr_acl_set(struct dentry *dentry, const char *name,
 
         if (value) {
                 acl = posix_acl_from_xattr(value, size);
+                if (IS_ERR(acl))
+                        return PTR_ERR(acl);
+
                 if (acl) {
                         ret = posix_acl_valid(acl);
                         if (ret)
                                 goto out;
-                } else if (IS_ERR(acl)) {
-                        return PTR_ERR(acl);
                 }
         }