Properly propagate out of memory errors.

src/channel.c

@@ -1036,6 +1036,10 @@ ssize_t _libssh2_channel_read_ex(LIBSSH2_CHANNEL *channel,
 	do {
 		rc = libssh2_packet_read(session);
 	} while (rc > 0);
+
+	if((rc < 0) && (rc != PACKET_EAGAIN)) {
+		return rc;
+	}
 	rc = 0;
 
 	/* restore blocking state */

src/hostkey.c

@@ -317,13 +317,13 @@ static int libssh2_hostkey_method_ssh_dss_signv(LIBSSH2_SESSION *session, unsign
 	unsigned int i;
 
 	*signature = LIBSSH2_ALLOC(session, 2 * SHA_DIGEST_LENGTH);
-	*signature_len = 2 * SHA_DIGEST_LENGTH;
-	memset(*signature, 0, 2 * SHA_DIGEST_LENGTH);
-
-	if (!(*signature)) {
+	if (!*signature) {
 		return -1;
 	}
 
+	*signature_len = 2 * SHA_DIGEST_LENGTH;
+	memset(*signature, 0, 2 * SHA_DIGEST_LENGTH);
+
 	libssh2_sha1_init(&ctx);
 	for(i = 0; i < veccount; i++) {
 		libssh2_sha1_update(ctx, datavec[i].iov_base, datavec[i].iov_len);

src/transport.c

@@ -220,7 +220,8 @@ static libssh2pack_t fullpacket(LIBSSH2_SESSION *session,
 
 	debugdump(session, "libssh2_packet_read() plain",
 		  p->payload, payload_len);
-        libssh2_packet_add(session, p->payload, payload_len, macstate);
+        if (libssh2_packet_add(session, p->payload, payload_len, macstate) < 0)
+		return PACKET_FAIL;
 
         return packet_type;
 }