From e4add0b010ed6f2180dcb05a13026242ed935334 Mon Sep 17 00:00:00 2001 From: Guy Harris Date: Sat, 18 Apr 2020 14:04:59 -0700 Subject: When un-escaping, don't allocate a too-large buffer. The buffer should be big enough to hold the captured data, but it doesn't need to be big enough to hold the entire on-the-network packet, if we haven't captured all of it. --- print-ppp.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) (limited to 'print-ppp.c') diff --git a/print-ppp.c b/print-ppp.c index a2fa67d7..6156e195 100644 --- a/print-ppp.c +++ b/print-ppp.c @@ -1404,19 +1404,28 @@ trunc: return 0; } +/* + * Un-escape RFC 1662 PPP in HDLC-like framing, with octet escapes. + * The length argument is the on-the-wire length, not the captured + * length; we can only un-escape the captured part. + */ static void ppp_hdlc(netdissect_options *ndo, const u_char *p, u_int length) { + u_int caplen = ndo->ndo_snapend - p; u_char *b, *t, c; const u_char *s; u_int i, proto; const void *se; + if (caplen == 0) + return; + if (length == 0) return; - b = (u_char *)nd_malloc(ndo, length); + b = (u_char *)nd_malloc(ndo, caplen); if (b == NULL) return; @@ -1425,11 +1434,11 @@ ppp_hdlc(netdissect_options *ndo, * Do this so that we dont overwrite the original packet * contents. */ - for (s = p, t = b, i = length; i != 0 && ND_TTEST_1(s); i--) { + for (s = p, t = b, i = caplen; i != 0; i--) { c = GET_U_1(s); s++; if (c == 0x7d) { - if (i <= 1 || !ND_TTEST_1(s)) + if (i <= 1) break; i--; c = GET_U_1(s) ^ 0x20; -- cgit v1.2.1