2 files changed, 17 insertions, 1 deletions
diff --git a/tap.c b/tap.c
index a47f9d3..7d9113a 100644
--- a/tap.c
+++ b/tap.c
@@ -1011,7 +1011,7 @@ void tap_handler_passt(struct ctx *c, uint32_t events,
 	}
 
 	while (n > (ssize_t)sizeof(uint32_t)) {
-		uint32_t l2len = ntohl(*(uint32_t *)p);
+		uint32_t l2len = ntohl_unaligned(p);
 
 		if (l2len < sizeof(struct ethhdr) || l2len > ETH_MAX_MTU) {
 			err("Bad frame size from guest, resetting connection");
diff --git a/util.h b/util.h
index 6f44eab..b7541ce 100644
--- a/util.h
+++ b/util.h
@@ -10,8 +10,10 @@
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stddef.h>
+#include <stdint.h>
 #include <string.h>
 #include <signal.h>
+#include <arpa/inet.h>
 
 #include "log.h"
 
@@ -116,6 +118,20 @@
 #define	htonl_constant(x)	(__bswap_constant_32(x))
 #endif
 
+/**
+ * ntohl_unaligned() - Read 32-bit BE value from a possibly unaligned address
+ * @p:		Pointer to the BE value in memory
+ *
+ * Returns: Host-order value of 32-bit BE quantity at @p
+ */
+static inline uint32_t ntohl_unaligned(const void *p)
+{
+	uint32_t val;
+
+	memcpy(&val, p, sizeof(val));
+	return ntohl(val);
+}
+
 #define NS_FN_STACK_SIZE	(RLIMIT_STACK_VAL * 1024 / 8)
 int do_clone(int (*fn)(void *), char *stack_area, size_t stack_size, int flags,
 	     void *arg);