Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6

Pull crypto fix from Herbert Xu:
 "This fixes a NULL pointer dereference in crypto_remove_spawns that can
  be triggered through af_alg"

* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  crypto: algapi - fix NULL dereference in crypto_remove_spawns()

1 files changed, 12 insertions, 0 deletions

diff --git a/crypto/algapi.c b/crypto/algapi.c
index 60d7366ed343..9a636f961572 100644
--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -167,6 +167,18 @@ void crypto_remove_spawns(struct crypto_alg *alg, struct list_head *list,
 
 			spawn->alg = NULL;
 			spawns = &inst->alg.cra_users;
+
+			/*
+			 * We may encounter an unregistered instance here, since
+			 * an instance's spawns are set up prior to the instance
+			 * being registered.  An unregistered instance will have
+			 * NULL ->cra_users.next, since ->cra_users isn't
+			 * properly initialized until registration.  But an
+			 * unregistered instance cannot have any users, so treat
+			 * it the same as ->cra_users being empty.
+			 */
+			if (spawns->next == NULL)
+				break;
 		}
 	} while ((spawns = crypto_more_spawns(alg, &stack, &top,
 					      &secondary_spawns)));