cgroups: avoid accessing uninitialized data in failure path

If cgroup_get_rootdir() failed, free_cg_links() will be called in the
failure path, but tmp_cg_links hasn't been initialized at that time.

I introduced this bug in the 2.6.27 merge window.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index a3415507bd0a..2606d0fb4e54 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1024,7 +1024,7 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
                 if (ret == -EBUSY) {
                         mutex_unlock(&cgroup_mutex);
                         mutex_unlock(&inode->i_mutex);
-                        goto drop_new_super;
+                        goto free_cg_links;
                 }
 
                 /* EBUSY should be the only error here */
@@ -1073,10 +1073,11 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
 
         return simple_set_mnt(mnt, sb);
 
+ free_cg_links:
+        free_cg_links(&tmp_cg_links);
  drop_new_super:
         up_write(&sb->s_umount);
         deactivate_super(sb);
-        free_cg_links(&tmp_cg_links);
         return ret;
 }