mempolicy: ERR_PTR dereference in mpol_shared_policy_init()

The original code called mpol_put(new) while "new" was an ERR_PTR.
Signed-off-by: NDan Carpenter <error27@gmail.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Acked-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/mempolicy.c

@@ -2098,7 +2098,7 @@ void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol)
 		/* contextualize the tmpfs mount point mempolicy */
 		new = mpol_new(mpol->mode, mpol->flags, &mpol->w.user_nodemask);
 		if (IS_ERR(new))
-			goto put_free; /* no valid nodemask intersection */
+			goto free_scratch; /* no valid nodemask intersection */
 
 		task_lock(current);
 		ret = mpol_set_nodemask(new, &mpol->w.user_nodemask, scratch);
@@ -2114,6 +2114,7 @@ void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol)
 
 put_free:
 		mpol_put(new);			/* drop initial ref */
+free_scratch:
 		NODEMASK_SCRATCH_FREE(scratch);
 	}
 }