e3a663f570
The ppp decapsulator in tcpdump 4.9.3 can be convinced to allocate a large amount of memory. Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com> Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
68 lines
1.9 KiB
Diff
68 lines
1.9 KiB
Diff
From 32027e199368dad9508965aae8cd8de5b6ab5231 Mon Sep 17 00:00:00 2001
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From: Guy Harris <guy@alum.mit.edu>
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Date: Sat, 18 Apr 2020 14:04:59 -0700
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Subject: [PATCH] PPP: When un-escaping, don't allocate a too-large buffer.
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The buffer should be big enough to hold the captured data, but it
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doesn't need to be big enough to hold the entire on-the-network packet,
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if we haven't captured all of it.
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(backported from commit e4add0b010ed6f2180dcb05a13026242ed935334)
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[Retrieved from:
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https://github.com/the-tcpdump-group/tcpdump/commit/32027e199368dad9508965aae8cd8de5b6ab5231]
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Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
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---
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print-ppp.c | 18 ++++++++++++++----
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1 file changed, 14 insertions(+), 4 deletions(-)
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diff --git a/print-ppp.c b/print-ppp.c
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index 891761728..33fb03412 100644
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--- a/print-ppp.c
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+++ b/print-ppp.c
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@@ -1367,19 +1367,29 @@ print_bacp_config_options(netdissect_options *ndo,
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return 0;
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}
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+/*
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+ * Un-escape RFC 1662 PPP in HDLC-like framing, with octet escapes.
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+ * The length argument is the on-the-wire length, not the captured
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+ * length; we can only un-escape the captured part.
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+ */
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static void
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ppp_hdlc(netdissect_options *ndo,
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const u_char *p, int length)
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{
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+ u_int caplen = ndo->ndo_snapend - p;
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u_char *b, *t, c;
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const u_char *s;
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- int i, proto;
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+ u_int i;
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+ int proto;
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const void *se;
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+ if (caplen == 0)
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+ return;
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+
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if (length <= 0)
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return;
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- b = (u_char *)malloc(length);
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+ b = (u_char *)malloc(caplen);
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if (b == NULL)
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return;
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@@ -1388,10 +1398,10 @@ ppp_hdlc(netdissect_options *ndo,
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* Do this so that we dont overwrite the original packet
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* contents.
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*/
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- for (s = p, t = b, i = length; i > 0 && ND_TTEST(*s); i--) {
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+ for (s = p, t = b, i = caplen; i != 0; i--) {
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c = *s++;
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if (c == 0x7d) {
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- if (i <= 1 || !ND_TTEST(*s))
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+ if (i <= 1)
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break;
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i--;
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c = *s++ ^ 0x20;
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