From: Francois-Xavier Le Bail <devel.fx.lebail@orange.fr>
Date: Tue, 17 Nov 2020 20:14:51 +0000 (+0100)
Subject: SLL/SLL2: Use ND_TCHECK_LEN() for bounds checks
X-Git-Tag: tcpdump-4.99-bp~56
X-Git-Url: https://git.tcpdump.org/tcpdump/commitdiff_plain/ab5a18ab1312d37e1aceded9960a97a23028235a

SLL/SLL2: Use ND_TCHECK_LEN() for bounds checks

Moreover:
Define ND_LONGJMP_FROM_TCHECK.
Remove 2 ndo_ll_hdr_len increments in truncation cases.
Remove 2 comments: "can't happen" is wrong (fuzzing, etc.)
---

diff --git a/print-sll.c b/print-sll.c
index ad0ae7f1..19d2973e 100644
--- a/print-sll.c
+++ b/print-sll.c
@@ -31,6 +31,7 @@
 
 #include "netdissect-stdinc.h"
 
+#define ND_LONGJMP_FROM_TCHECK
 #include "netdissect.h"
 #include "addrtoname.h"
 #include "ethertype.h"
@@ -223,16 +224,7 @@ sll_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char
 	u_int hdrlen;
 
 	ndo->ndo_protocol = "sll";
-	if (caplen < SLL_HDR_LEN) {
-		/*
-		 * XXX - this "can't happen" because "pcap-linux.c" always
-		 * adds this many bytes of header to every packet in a
-		 * cooked socket capture.
-		 */
-		nd_print_trunc(ndo);
-		ndo->ndo_ll_hdr_len += caplen;
-		return;
-	}
+	ND_TCHECK_LEN(p, SLL_HDR_LEN);
 
 	sllp = (const struct sll_header *)p;
 
@@ -419,16 +411,7 @@ sll2_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char
 #endif
 
 	ndo->ndo_protocol = "sll2";
-	if (caplen < SLL2_HDR_LEN) {
-		/*
-		 * XXX - this "can't happen" because "pcap-linux.c" always
-		 * adds this many bytes of header to every packet in a
-		 * cooked socket capture.
-		 */
-		nd_print_trunc(ndo);
-		ndo->ndo_ll_hdr_len += caplen;
-		return;
-	}
+	ND_TCHECK_LEN(p, SLL2_HDR_LEN);
 
 	sllp = (const struct sll2_header *)p;
 #ifdef HAVE_NET_IF_H