From 32027e199368dad9508965aae8cd8de5b6ab5231 Mon Sep 17 00:00:00 2001 From: Guy Harris Date: Sat, 18 Apr 2020 14:04:59 -0700 Subject: [PATCH] PPP: 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. (backported from commit e4add0b010ed6f2180dcb05a13026242ed935334) [Retrieved from: https://github.com/the-tcpdump-group/tcpdump/commit/32027e199368dad9508965aae8cd8de5b6ab5231] Signed-off-by: Fabrice Fontaine --- print-ppp.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/print-ppp.c b/print-ppp.c index 891761728..33fb03412 100644 --- a/print-ppp.c +++ b/print-ppp.c @@ -1367,19 +1367,29 @@ print_bacp_config_options(netdissect_options *ndo, 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, int length) { + u_int caplen = ndo->ndo_snapend - p; u_char *b, *t, c; const u_char *s; - int i, proto; + u_int i; + int proto; const void *se; + if (caplen == 0) + return; + if (length <= 0) return; - b = (u_char *)malloc(length); + b = (u_char *)malloc(caplen); if (b == NULL) return; @@ -1388,10 +1398,10 @@ 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(*s); i--) { + for (s = p, t = b, i = caplen; i != 0; i--) { c = *s++; if (c == 0x7d) { - if (i <= 1 || !ND_TTEST(*s)) + if (i <= 1) break; i--; c = *s++ ^ 0x20;