fs: NULL dereference in posix_acl_to_xattr()

This patch moves the dereference of "buffer" after the check for NULL.
The only place which passes a NULL parameter is gfs2_set_acl().

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 38bae5a0ea25..202b84fd3310 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -717,7 +717,7 @@ posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
                    void *buffer, size_t size)
 {
         posix_acl_xattr_header *ext_acl = (posix_acl_xattr_header *)buffer;
-        posix_acl_xattr_entry *ext_entry = ext_acl->a_entries;
+        posix_acl_xattr_entry *ext_entry;
         int real_size, n;
 
         real_size = posix_acl_xattr_size(acl->a_count);
@@ -725,7 +725,8 @@ posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
                 return real_size;
         if (real_size > size)
                 return -ERANGE;
-        
+
+        ext_entry = ext_acl->a_entries;
         ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
 
         for (n=0; n < acl->a_count; n++, ext_entry++) {