tcpdump/print-cip.c
Guy Harris 4ef024c8e9 CVE-2016-7992/When comparing against an LLC+SNAP header, check only the bytes we have.
Fixes a heap overflow found with American Fuzzy Lop by Hanno Böck.

Fix a length value to be unsigned while we're at it.
2017-01-18 09:16:35 +01:00

109 lines
2.5 KiB
C

/*
* Marko Kiiskila carnil@cs.tut.fi
*
* Tampere University of Technology - Telecommunications Laboratory
*
* Permission to use, copy, modify and distribute this
* software and its documentation is hereby granted,
* provided that both the copyright notice and this
* permission notice appear in all copies of the software,
* derivative works or modified versions, and any portions
* thereof, that both notices appear in supporting
* documentation, and that the use of this software is
* acknowledged in any publications resulting from using
* the software.
*
* TUT ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION AND DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS
* SOFTWARE.
*
*/
/* \summary: Classical-IP over ATM printer */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <string.h>
#include <netdissect-stdinc.h>
#include "netdissect.h"
#include "addrtoname.h"
static const unsigned char rfcllc[] = {
0xaa, /* DSAP: non-ISO */
0xaa, /* SSAP: non-ISO */
0x03, /* Ctrl: Unnumbered Information Command PDU */
0x00, /* OUI: EtherType */
0x00,
0x00 };
static inline void
cip_print(netdissect_options *ndo, u_int length)
{
/*
* There is no MAC-layer header, so just print the length.
*/
ND_PRINT((ndo, "%u: ", length));
}
/*
* This is the top level routine of the printer. 'p' points
* to the LLC/SNAP or raw header of the packet, 'h->ts' is the timestamp,
* 'h->len' is the length of the packet off the wire, and 'h->caplen'
* is the number of bytes actually captured.
*/
u_int
cip_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
{
u_int caplen = h->caplen;
u_int length = h->len;
size_t cmplen;
int llc_hdrlen;
cmplen = sizeof(rfcllc);
if (cmplen > caplen)
cmplen = caplen;
if (cmplen > length)
cmplen = length;
if (ndo->ndo_eflag)
cip_print(ndo, length);
if (cmplen == 0) {
ND_PRINT((ndo, "[|cip]"));
return 0;
}
if (memcmp(rfcllc, p, cmplen) == 0) {
/*
* LLC header is present. Try to print it & higher layers.
*/
llc_hdrlen = llc_print(ndo, p, length, caplen, NULL, NULL);
if (llc_hdrlen < 0) {
/* packet type not known, print raw packet */
if (!ndo->ndo_suppress_default_print)
ND_DEFAULTPRINT(p, caplen);
llc_hdrlen = -llc_hdrlen;
}
} else {
/*
* LLC header is absent; treat it as just IP.
*/
llc_hdrlen = 0;
ip_print(ndo, p, length);
}
return (llc_hdrlen);
}
/*
* Local Variables:
* c-style: whitesmith
* c-basic-offset: 8
* End:
*/