From e3a663f5705c492f52128b4a7ff514480332b6df Mon Sep 17 00:00:00 2001 From: Fabrice Fontaine Date: Fri, 13 Nov 2020 21:21:15 +0100 Subject: [PATCH] package/tcpdump: fix CVE-2020-8037 The ppp decapsulator in tcpdump 4.9.3 can be convinced to allocate a large amount of memory. Signed-off-by: Fabrice Fontaine Signed-off-by: Peter Korsgaard --- ...ng-don-t-allocate-a-too-large-buffer.patch | 67 +++++++++++++++++++ package/tcpdump/tcpdump.mk | 3 + 2 files changed, 70 insertions(+) create mode 100644 package/tcpdump/0001-PPP-When-un-escaping-don-t-allocate-a-too-large-buffer.patch diff --git a/package/tcpdump/0001-PPP-When-un-escaping-don-t-allocate-a-too-large-buffer.patch b/package/tcpdump/0001-PPP-When-un-escaping-don-t-allocate-a-too-large-buffer.patch new file mode 100644 index 0000000000..9e8674ac90 --- /dev/null +++ b/package/tcpdump/0001-PPP-When-un-escaping-don-t-allocate-a-too-large-buffer.patch @@ -0,0 +1,67 @@ +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; diff --git a/package/tcpdump/tcpdump.mk b/package/tcpdump/tcpdump.mk index 01a46b9b5f..8db35694ea 100644 --- a/package/tcpdump/tcpdump.mk +++ b/package/tcpdump/tcpdump.mk @@ -18,6 +18,9 @@ TCPDUMP_CONF_OPTS = \ $(if $(BR2_PACKAGE_TCPDUMP_SMB),--enable-smb,--disable-smb) TCPDUMP_DEPENDENCIES = libpcap +# 0001-PPP-When-un-escaping-don-t-allocate-a-too-large-buffer.patch +TCPDUMP_IGNORE_CVES += CVE-2020-8037 + ifeq ($(BR2_STATIC_LIBS),y) TCPDUMP_CONF_OPTS += LIBS="`$(STAGING_DIR)/usr/bin/pcap-config --static --additional-libs`" endif -- 2.30.2