Don't use undefined behaviour.

gtests/net/packetdrill/checksum.c

@@ -239,7 +239,7 @@ static u32 crc_c[256] = {
 __be32 sctp_crc32c(const void *packet, u32 len)
 {
 	u32 i, crc32c;
-	u8 byte0, byte1, byte2, byte3;
+	u32 byte0, byte1, byte2, byte3;
 	const u8 *buf = (const u8 *)packet;
 
 	crc32c = ~0;

gtests/net/packetdrill/ip_address.c

@@ -309,7 +309,7 @@ extern int netmask_to_prefix(const char *netmask)
 	int prefix_len = 0;
 
 	for (pos = 31; pos >= 0; --pos) {
-		if (!(mask_addr & (1<<pos)))
+		if (!(mask_addr & (1U<<pos)))
 			break;
 		++prefix_len;
 	}