File tcpdump-CVE-2018-14461.patch of Package tcpdump.17077

From aa5c6b710dfd8020d2c908d6b3bd41f1da719b3b Mon Sep 17 00:00:00 2001
From: Francois-Xavier Le Bail <devel.fx.lebail@orange.fr>
Date: Sun, 8 Oct 2017 11:49:24 +0200
Subject: [PATCH] (for 4.9.3) CVE-2018-14461/LDP: Fix a bounds check

In ldp_tlv_print(), the FT Session TLV length must be 12, not 8 (RFC3479)

This fixes a buffer over-read discovered by Konrad Rieck and
Bhargava Shastry.

Add a test using the capture file supplied by the reporter(s).

Moreover:
Add and use tstr[].
Add a comment.
---
 print-ldp.c                       |   9 ++++++---
 tests/TESTLIST                    |   1 +
 tests/ldp-ldp_tlv_print-oobr.out  |   6 ++++++
 tests/ldp-ldp_tlv_print-oobr.pcap | Bin 0 -> 395 bytes
 4 files changed, 13 insertions(+), 3 deletions(-)
 create mode 100644 tests/ldp-ldp_tlv_print-oobr.out
 create mode 100644 tests/ldp-ldp_tlv_print-oobr.pcap

diff --git a/print-ldp.c b/print-ldp.c
index 1bb27fe41..afd943d0a 100644
--- a/print-ldp.c
+++ b/print-ldp.c
@@ -29,6 +29,8 @@
 #include "l2vpn.h"
 #include "af.h"
 
+static const char tstr[] = " [|LDP]";
+
 /*
  * ldp common header
  *
@@ -486,7 +488,7 @@ ldp_tlv_print(netdissect_options *ndo,
 	break;
 
     case LDP_TLV_FT_SESSION:
-	TLV_TCHECK(8);
+	TLV_TCHECK(12);
 	ft_flags = EXTRACT_16BITS(tptr);
 	ND_PRINT((ndo, "\n\t      Flags: [%sReconnect, %sSave State, %sAll-Label Protection, %s Checkpoint, %sRe-Learn State]",
 	       ft_flags&0x8000 ? "" : "No ",
@@ -494,6 +496,7 @@ ldp_tlv_print(netdissect_options *ndo,
 	       ft_flags&0x4 ? "" : "No ",
 	       ft_flags&0x2 ? "Sequence Numbered Label" : "All Labels",
 	       ft_flags&0x1 ? "" : "Don't "));
+	/* 16 bits (FT Flags) + 16 bits (Reserved) */
 	tptr+=4;
 	ui = EXTRACT_32BITS(tptr);
 	if (ui)
@@ -534,7 +537,7 @@ ldp_tlv_print(netdissect_options *ndo,
     return(tlv_len+4); /* Type & Length fields not included */
 
 trunc:
-    ND_PRINT((ndo, "\n\t\t packet exceeded snapshot"));
+    ND_PRINT((ndo, "%s", tstr));
     return 0;
 
 badtlv:
@@ -692,7 +695,7 @@ ldp_pdu_print(netdissect_options *ndo,
     }
     return pdu_len+4;
 trunc:
-    ND_PRINT((ndo, "\n\t\t packet exceeded snapshot"));
+    ND_PRINT((ndo, "%s", tstr));
     return 0;
 }