From: Roy Marples <roy@marples.name>
Date: Wed, 5 Feb 2020 14:54:49 +0000 (+0000)
Subject: ARP: Only copy out frame header if we have it.
X-Git-Tag: v8.1.7~16
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=60bde9c63e01f1932e0ce782946989f942739dfb;p=thirdparty%2Fdhcpcd.git

ARP: Only copy out frame header if we have it.

Frameless does exist.
---

diff --git a/src/arp.c b/src/arp.c
index 6e3d634a..15925a8f 100644
--- a/src/arp.c
+++ b/src/arp.c
@@ -228,16 +228,18 @@ arp_packet(struct interface *ifp, uint8_t *data, size_t len)
 
 	/* Copy the frame header source and destination out */
 	memset(&arm, 0, sizeof(arm));
-	hw_s = bpf_frame_header_src(ifp, data, &falen);
-	if (hw_s != NULL && falen <= sizeof(arm.fsha))
-		memcpy(arm.fsha, hw_s, falen);
-	hw_t = bpf_frame_header_dst(ifp, data, &falen);
-	if (hw_t != NULL && falen <= sizeof(arm.ftha))
-		memcpy(arm.ftha, hw_t, falen);
-
-	/* Skip past the frame header */
-	data += fl;
-	len -= fl;
+	if (fl != 0) {
+		hw_s = bpf_frame_header_src(ifp, data, &falen);
+		if (hw_s != NULL && falen <= sizeof(arm.fsha))
+			memcpy(arm.fsha, hw_s, falen);
+		hw_t = bpf_frame_header_dst(ifp, data, &falen);
+		if (hw_t != NULL && falen <= sizeof(arm.ftha))
+			memcpy(arm.ftha, hw_t, falen);
+
+		/* Skip past the frame header */
+		data += fl;
+		len -= fl;
+	}
 
 	/* We must have a full ARP header */
 	if (len < sizeof(ar))