dhcpv4: fix out of bound access in dhcpv4_put

[project/odhcpd.git] / src / dhcpv4.c

diff --git a/src/dhcpv4.c b/src/dhcpv4.c
index 2b30307..b803359 100644 (file)
--- a/src/dhcpv4.c
+++ b/src/dhcpv4.c
@@ -493,7 +493,9 @@ static void dhcpv4_put(struct dhcpv4_message *msg, uint8_t **cookie,
                uint8_t type, uint8_t len, const void *data)
 {
        uint8_t *c = *cookie;
-       if (*cookie + 2 + len > (uint8_t*)&msg[1])
+       uint8_t *end = (uint8_t *)msg + sizeof(*msg);
+
+       if (*cookie + 2 + len > end)
                return;
 
        *c++ = type;