libjson-c: backport security fixes

This backports upstream fixes for the out of bounds write vulnerability in json-c.
It was reported and patches in this upstream PR: https://github.com/json-c/json-c/pull/592

Addresses CVE-2020-12762

Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Signed-off-by: Luka Perkov <luka.perkov@sartura.hr>
[bump PKG_RELEASE]
Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 86 insertions, 0 deletions

diff --git a/package/libs/libjson-c/patches/003-Fix-integer-overflows.patch b/package/libs/libjson-c/patches/003-Fix-integer-overflows.patch
new file mode 100644
index 0000000000..2fac62df59
--- /dev/null
+++ b/package/libs/libjson-c/patches/003-Fix-integer-overflows.patch
@@ -0,0 +1,86 @@
+From d07b91014986900a3a75f306d302e13e005e9d67 Mon Sep 17 00:00:00 2001
+From: Tobias Stoeckmann <tobias@stoeckmann.org>
+Date: Mon, 4 May 2020 19:47:25 +0200
+Subject: [PATCH] Fix integer overflows.
+
+The data structures linkhash and printbuf are limited to 2 GB in size
+due to a signed integer being used to track their current size.
+
+If too much data is added, then size variable can overflow, which is
+an undefined behaviour in C programming language.
+
+Assuming that a signed int overflow just leads to a negative value,
+like it happens on many sytems (Linux i686/amd64 with gcc), then
+printbuf is vulnerable to an out of boundary write on 64 bit systems.
+---
+ linkhash.c |  7 +++++--
+ printbuf.c | 19 ++++++++++++++++---
+ 2 files changed, 21 insertions(+), 5 deletions(-)
+
+--- a/linkhash.c
++++ b/linkhash.c
+@@ -579,9 +579,12 @@ int lh_table_insert_w_hash(struct lh_tab
+ {
+ 	unsigned long n;
+ 
+-	if (t->count >= t->size * LH_LOAD_FACTOR)
+-		if (lh_table_resize(t, t->size * 2) != 0)
++	if (t->count >= t->size * LH_LOAD_FACTOR) {
++		/* Avoid signed integer overflow with large tables. */
++		int new_size = INT_MAX / 2 < t->size ? t->size * 2 : INT_MAX;
++		if (t->size == INT_MAX || lh_table_resize(t, new_size) != 0)
+ 			return -1;
++	}
+ 
+ 	n = h % t->size;
+ 
+--- a/printbuf.c
++++ b/printbuf.c
+@@ -15,6 +15,7 @@
+ 
+ #include "config.h"
+ 
++#include <limits.h>
+ #include <stdio.h>
+ #include <stdlib.h>
+ #include <string.h>
+@@ -65,9 +66,16 @@ static int printbuf_extend(struct printb
+ 	if (p->size >= min_size)
+ 		return 0;
+ 
+-	new_size = p->size * 2;
+-	if (new_size < min_size + 8)
+-		new_size =  min_size + 8;
++	/* Prevent signed integer overflows with large buffers. */
++  if (min_size > INT_MAX - 8)
++    return -1;
++  if (p->size > INT_MAX / 2)
++    new_size = min_size + 8;
++  else {
++    new_size = p->size * 2;
++    if (new_size < min_size + 8)
++      new_size = min_size + 8;
++  }
+ #ifdef PRINTBUF_DEBUG
+ 	MC_DEBUG("printbuf_memappend: realloc "
+ 	  "bpos=%d min_size=%d old_size=%d new_size=%d\n",
+@@ -82,6 +90,9 @@ static int printbuf_extend(struct printb
+ 
+ int printbuf_memappend(struct printbuf *p, const char *buf, int size)
+ {
++  /* Prevent signed integer overflows with large buffers. */
++  if (size > INT_MAX - p->bpos - 1)
++    return -1;
+   if (p->size <= p->bpos + size + 1) {
+     if (printbuf_extend(p, p->bpos + size + 1) < 0)
+       return -1;
+@@ -98,6 +109,9 @@ int printbuf_memset(struct printbuf *pb,
+ 
+ 	if (offset == -1)
+ 		offset = pb->bpos;
++	/* Prevent signed integer overflows with large buffers. */
++	if (len > INT_MAX - offset)
++		return -1;
+ 	size_needed = offset + len;
+ 	if (pb->size < size_needed)
+ 	{