Fix error handling in bn_exp

In the event of an error |rr| could be NULL. Therefore don't assume you can
use |rr| in the error handling code.

Reviewed-by: Andy Polyakov <appro@openssl.org>
(cherry picked from commit 8c5a7b33c6269c3bd6bc0df6b4c22e4fba03b485)

diff --git a/crypto/bn/bn_exp.c b/crypto/bn/bn_exp.c
index fca401450a3311b8086e2981765270bfe3ca67e7..27146c89e74001f5574c47ca0db091500ce48b20 100644 (file)
--- a/crypto/bn/bn_exp.c
+++ b/crypto/bn/bn_exp.c
@@ -168,10 +168,10 @@ int BN_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
                 goto err;
         }
     }
-    ret = 1;
- err:
     if (r != rr)
         BN_copy(r, rr);
+    ret = 1;
+ err:
     BN_CTX_end(ctx);
     bn_check_top(r);
     return (ret);