From: Guy Harris <guy@alum.mit.edu>
Date: Thu, 23 Oct 2014 07:06:32 +0000 (-0700)
Subject: Don't run past the snapshot length when doing hex/ASCII dumps.
X-Git-Url: https://git.tcpdump.org/tcpdump/commitdiff_plain/8079e28185d34d3bb4d195e21cb87d5fa8598601

Don't run past the snapshot length when doing hex/ASCII dumps.
---

diff --git a/print-ascii.c b/print-ascii.c
index fa8793cb..65815bde 100644
--- a/print-ascii.c
+++ b/print-ascii.c
@@ -59,8 +59,12 @@ static const char rcsid[] _U_ =
 void
 ascii_print(register const u_char *cp, register u_int length)
 {
+	u_int caplength;
 	register int s;
 
+	caplength = (snapend >= cp) ? snapend - cp : 0;
+	if (length > caplength)
+		length = caplength;
 	putchar('\n');
 	while (length > 0) {
 		s = *cp++;
@@ -77,12 +81,16 @@ void
 hex_and_ascii_print_with_offset(register const char *ident,
     register const u_char *cp, register u_int length, register u_int oset)
 {
+	u_int caplength;
 	register u_int i;
 	register int s1, s2;
 	register int nshorts;
 	char hexstuff[HEXDUMP_SHORTS_PER_LINE*HEXDUMP_HEXSTUFF_PER_SHORT+1], *hsp;
 	char asciistuff[ASCII_LINELENGTH+1], *asp;
 
+	caplength = (snapend >= cp) ? snapend - cp : 0;
+	if (length > caplength)
+		length = caplength;
 	nshorts = length / sizeof(u_short);
 	i = 0;
 	hsp = hexstuff; asp = asciistuff;
@@ -134,9 +142,13 @@ void
 hex_print_with_offset(register const char *ident, register const u_char *cp, register u_int length,
 		      register u_int oset)
 {
+	u_int caplength;
 	register u_int i, s;
 	register int nshorts;
 
+	caplength = (snapend >= cp) ? snapend - cp : 0;
+	if (length > caplength)
+		length = caplength;
 	nshorts = (u_int) length / sizeof(u_short);
 	i = 0;
 	while (--nshorts >= 0) {
diff --git a/tcpdump.c b/tcpdump.c
index cdfba892..88295d84 100644
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -1720,6 +1720,11 @@ print_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
                 hdrlen = (*print_info->p.printer)(h, sp);
         }
                 
+	/*
+	 * Restore the original snapend, as a printer might have
+	 * changed it.
+	 */
+	snapend = sp + h->caplen;
 	if (Xflag) {
 		/*
 		 * Print the raw packet data in hex and ASCII.