tcpdump: Fix CVE-2018-16301

This fixes the following security problem:
The command-line argument parser in tcpdump before 4.99.0 has a buffer
overflow in tcpdump.c:read_infile(). To trigger this vulnerability the
attacker needs to create a 4GB file on the local filesystem and to
specify the file name as the value of the -F command-line argument of
tcpdump.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

package/network/utils/tcpdump/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=tcpdump
 PKG_VERSION:=4.9.3
-PKG_RELEASE:=3
+PKG_RELEASE:=4
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=http://www.tcpdump.org/release/

package/network/utils/tcpdump/patches/102-CVE-2018-16301.patch

@@ -0,0 +1,101 @@
+From 8ab211a7ec728bb0ad8c766c8eeb12deb0a13b86 Mon Sep 17 00:00:00 2001
+From: Guy Harris <gharris@sonic.net>
+Date: Wed, 30 Sep 2020 11:37:30 -0700
+Subject: [PATCH] Handle very large -f files by rejecting them.
+
+_read(), on Windows, has a 32-bit size argument and a 32-bit return
+value, so reject -f files that have more than 2^31-1 characters.
+
+Add some #defines so that, on Windows, we use _fstati64 to get the size
+of that file, to handle large files.
+
+Don't assume that our definition for ssize_t is the same size as size_t;
+by the time we want to print the return value of the read, we know it'll
+fit into an int, so just cast it to int and print it with %d.
+
+(cherry picked from commit faf8fb70af3a013e5d662b8283dec742fd6b1a77)
+---
+ netdissect-stdinc.h | 16 +++++++++++++++-
+ tcpdump.c           | 15 ++++++++++++---
+ 2 files changed, 27 insertions(+), 4 deletions(-)
+
+--- a/netdissect-stdinc.h
++++ b/netdissect-stdinc.h
+@@ -149,10 +149,17 @@
+ #ifdef _MSC_VER
+ #define stat _stat
+ #define open _open
+-#define fstat _fstat
+ #define read _read
+ #define close _close
+ #define O_RDONLY _O_RDONLY
++
++/*
++ * We define our_fstat64 as _fstati64, and define our_statb as
++ * struct _stati64, so we get 64-bit file sizes.
++ */
++#define our_fstat _fstati64
++#define our_statb struct _stati64
++
+ #endif  /* _MSC_VER */
+ 
+ /*
+@@ -211,6 +218,13 @@ typedef char* caddr_t;
+ 
+ #include <arpa/inet.h>
+ 
++/*
++ * We should have large file support enabled, if it's available,
++ * so just use fstat as our_fstat and struct stat as our_statb.
++ */
++#define our_fstat fstat
++#define our_statb struct stat
++
+ #endif /* _WIN32 */
+ 
+ #ifndef HAVE___ATTRIBUTE__
+--- a/tcpdump.c
++++ b/tcpdump.c
+@@ -108,6 +108,7 @@ The Regents of the University of Califor
+ #endif /* HAVE_CAP_NG_H */
+ #endif /* HAVE_LIBCAP_NG */
+ 
++#include "netdissect-stdinc.h"
+ #include "netdissect.h"
+ #include "interface.h"
+ #include "addrtoname.h"
+@@ -861,15 +862,22 @@ read_infile(char *fname)
+ {
+ 	register int i, fd, cc;
+ 	register char *cp;
+-	struct stat buf;
++	our_statb buf;
+ 
+ 	fd = open(fname, O_RDONLY|O_BINARY);
+ 	if (fd < 0)
+ 		error("can't open %s: %s", fname, pcap_strerror(errno));
+ 
+-	if (fstat(fd, &buf) < 0)
++	if (our_fstat(fd, &buf) < 0)
+ 		error("can't stat %s: %s", fname, pcap_strerror(errno));
+ 
++	/*
++	 * Reject files whose size doesn't fit into an int; a filter
++	 * *that* large will probably be too big.
++	 */
++	if (buf.st_size > INT_MAX)
++		error("%s is too large", fname);
++
+ 	cp = malloc((u_int)buf.st_size + 1);
+ 	if (cp == NULL)
+ 		error("malloc(%d) for %s: %s", (u_int)buf.st_size + 1,
+@@ -878,7 +886,8 @@ read_infile(char *fname)
+ 	if (cc < 0)
+ 		error("read %s: %s", fname, pcap_strerror(errno));
+ 	if (cc != buf.st_size)
+-		error("short read %s (%d != %d)", fname, cc, (int)buf.st_size);
++		error("short read %s (%d != %d)", fname, (int) cc,
++		    (int)buf.st_size);
+ 
+ 	close(fd);
+ 	/* replace "# comment" with spaces */