Improve robustness of DER recoding code

как в https://github.com/bitcoin/bitcoin/commit/8d0fd4646099132f0a68d6c3d0da3a6a10ab9631

diff --git a/src/key.cpp b/src/key.cpp
index 1b3f380..c37ad83 100644 (file)
--- a/src/key.cpp
+++ b/src/key.cpp
@@ -456,7 +456,18 @@ bool CKey::Verify(uint256 hash, const std::vector<unsigned char>& vchSig)
     unsigned char *norm_der = NULL;
     ECDSA_SIG *norm_sig = ECDSA_SIG_new();
     const unsigned char* sigptr = &vchSig[0];
-    d2i_ECDSA_SIG(&norm_sig, &sigptr, vchSig.size());
+    assert(norm_sig);
+    if (d2i_ECDSA_SIG(&norm_sig, &sigptr, vchSig.size()) == NULL)
+    {
+        /* As of OpenSSL 1.0.0p d2i_ECDSA_SIG frees and nulls the pointer on
+        * error. But OpenSSL's own use of this function redundantly frees the
+        * result. As ECDSA_SIG_free(NULL) is a no-op, and in the absence of a
+        * clear contract for the function behaving the same way is more
+        * conservative.
+        */
+        ECDSA_SIG_free(norm_sig);
+        return false;
+    }
     int derlen = i2d_ECDSA_SIG(norm_sig, &norm_der);
     ECDSA_SIG_free(norm_sig);
     if (derlen <= 0)