123 lines
3.6 KiB
Diff
123 lines
3.6 KiB
Diff
From b9811ef5bb1b7d45a90e042f81f3aaf233c8bcb2 Mon Sep 17 00:00:00 2001
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From: Guy Harris <gharris@sonic.net>
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Date: Tue, 12 Mar 2024 00:37:23 -0700
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Subject: [PATCH] ppp: use the buffer stack for the de-escaping buffer.
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This both saves the buffer for freeing later and saves the packet
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pointer and snapend to be restored when packet processing is complete,
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even if an exception is thrown with longjmp.
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This means that the hex/ASCII printing in pretty_print_packet()
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processes the packet data as captured or read from the savefile, rather
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than as modified by the PPP printer, so that the bounds checking is
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correct.
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That fixes CVE-2024-2397, which was caused by an exception being thrown
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by the hex/ASCII printer (which should only happen if those routines are
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called by a packet printer, not if they're called for the -X/-x/-A
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flag), which jumps back to the setjmp() that surrounds the packet
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printer. Hilarity^Winfinite looping ensues.
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Also, restore ndo->ndo_packetp before calling the hex/ASCII printing
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routine, in case nd_pop_all_packet_info() didn't restore it.
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---
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print-ppp.c | 31 +++++++++++++++++--------------
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print.c | 8 ++++++--
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2 files changed, 23 insertions(+), 16 deletions(-)
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diff --git a/print-ppp.c b/print-ppp.c
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index 2cf06c363..9aed23eb9 100644
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--- a/print-ppp.c
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+++ b/print-ppp.c
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@@ -37,6 +37,8 @@
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#include "netdissect-stdinc.h"
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+#include <stdlib.h>
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+
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#ifdef __bsdi__
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#include <net/slcompress.h>
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#include <net/if_ppp.h>
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@@ -1358,7 +1360,6 @@ ppp_hdlc(netdissect_options *ndo,
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u_char *b, *t, c;
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const u_char *s;
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u_int i, proto;
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- const void *sb, *se;
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if (caplen == 0)
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return;
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@@ -1366,9 +1367,11 @@ ppp_hdlc(netdissect_options *ndo,
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if (length == 0)
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return;
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- b = (u_char *)nd_malloc(ndo, caplen);
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- if (b == NULL)
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- return;
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+ b = (u_char *)malloc(caplen);
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+ if (b == NULL) {
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+ (*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC,
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+ "%s: malloc", __func__);
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+ }
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/*
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* Unescape all the data into a temporary, private, buffer.
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@@ -1389,13 +1392,15 @@ ppp_hdlc(netdissect_options *ndo,
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}
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/*
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- * Change the end pointer, so bounds checks work.
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- * Change the pointer to packet data to help debugging.
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+ * Switch to the output buffer for dissection, and save it
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+ * on the buffer stack so it can be freed; our caller must
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+ * pop it when done.
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*/
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- sb = ndo->ndo_packetp;
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- se = ndo->ndo_snapend;
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- ndo->ndo_packetp = b;
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- ndo->ndo_snapend = t;
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+ if (!nd_push_buffer(ndo, b, b, (u_int)(t - b))) {
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+ free(b);
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+ (*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC,
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+ "%s: can't push buffer on buffer stack", __func__);
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+ }
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length = ND_BYTES_AVAILABLE_AFTER(b);
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/* now lets guess about the payload codepoint format */
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@@ -1437,13 +1442,11 @@ ppp_hdlc(netdissect_options *ndo,
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}
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cleanup:
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- ndo->ndo_packetp = sb;
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- ndo->ndo_snapend = se;
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+ nd_pop_packet_info(ndo);
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return;
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trunc:
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- ndo->ndo_packetp = sb;
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- ndo->ndo_snapend = se;
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+ nd_pop_packet_info(ndo);
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nd_print_trunc(ndo);
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}
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diff --git a/print.c b/print.c
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index b9ba5997d..f20633388 100644
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--- a/print.c
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+++ b/print.c
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@@ -431,10 +431,14 @@ pretty_print_packet(netdissect_options *ndo, const struct pcap_pkthdr *h,
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nd_pop_all_packet_info(ndo);
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/*
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- * Restore the original snapend, as a printer might have
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- * changed it.
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+ * Restore the originals snapend and packetp, as a printer
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+ * might have changed them.
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+ *
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+ * XXX - nd_pop_all_packet_info() should have restored the
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+ * original values, but, just in case....
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*/
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ndo->ndo_snapend = sp + h->caplen;
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+ ndo->ndo_packetp = sp;
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if (ndo->ndo_Xflag) {
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/*
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* Print the raw packet data in hex and ASCII.
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