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>

5 files changed, 175 insertions, 1 deletions

diff --git a/package/libs/libjson-c/Makefile b/package/libs/libjson-c/Makefile
index b61d99cc99..f02518310a 100644
--- a/package/libs/libjson-c/Makefile
+++ b/package/libs/libjson-c/Makefile
@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=json-c
 PKG_VERSION:=0.13.1
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION)-nodoc.tar.gz
 PKG_SOURCE_URL:=https://s3.amazonaws.com/json-c_releases/releases/
diff --git a/package/libs/libjson-c/patches/001-Protect-array_list_del_idx-against-size_t-overflow.patch b/package/libs/libjson-c/patches/001-Protect-array_list_del_idx-against-size_t-overflow.patch
new file mode 100644
index 0000000000..456fbf35ff
--- /dev/null
+++ b/package/libs/libjson-c/patches/001-Protect-array_list_del_idx-against-size_t-overflow.patch
@@ -0,0 +1,27 @@
+From 099016b7e8d70a6d5dd814e788bba08d33d48426 Mon Sep 17 00:00:00 2001
+From: Tobias Stoeckmann <tobias@stoeckmann.org>
+Date: Mon, 4 May 2020 19:41:16 +0200
+Subject: [PATCH 1/2] Protect array_list_del_idx against size_t overflow.
+
+If the assignment of stop overflows due to idx and count being
+larger than SIZE_T_MAX in sum, out of boundary access could happen.
+
+It takes invalid usage of this function for this to happen, but
+I decided to add this check so array_list_del_idx is as safe against
+bad usage as the other arraylist functions.
+---
+ arraylist.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+--- a/arraylist.c
++++ b/arraylist.c
+@@ -135,6 +135,9 @@ array_list_del_idx( struct array_list *a
+ {
+ 	size_t i, stop;
+ 
++	/* Avoid overflow in calculation with large indices. */
++	if (idx > SIZE_T_MAX - count)
++		return -1;
+ 	stop = idx + count;
+ 	if ( idx >= arr->length || stop > arr->length ) return -1;
+ 	for ( i = idx; i < stop; ++i ) {
diff --git a/package/libs/libjson-c/patches/002-Prevent-division-by-zero-in-linkhash.patch b/package/libs/libjson-c/patches/002-Prevent-division-by-zero-in-linkhash.patch
new file mode 100644
index 0000000000..d37fe5857b
--- /dev/null
+++ b/package/libs/libjson-c/patches/002-Prevent-division-by-zero-in-linkhash.patch
@@ -0,0 +1,32 @@
+From 77d935b7ae7871a1940cd827e850e6063044ec45 Mon Sep 17 00:00:00 2001
+From: Tobias Stoeckmann <tobias@stoeckmann.org>
+Date: Mon, 4 May 2020 19:46:45 +0200
+Subject: [PATCH 2/2] Prevent division by zero in linkhash.
+
+If a linkhash with a size of zero is created, then modulo operations
+are prone to division by zero operations.
+
+Purely protective measure against bad usage.
+---
+ linkhash.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+--- a/linkhash.c
++++ b/linkhash.c
+@@ -12,6 +12,7 @@
+ 
+ #include "config.h"
+ 
++#include <assert.h>
+ #include <stdio.h>
+ #include <string.h>
+ #include <stdlib.h>
+@@ -498,6 +499,8 @@ struct lh_table* lh_table_new(int size,
+ 	int i;
+ 	struct lh_table *t;
+ 
++  /* Allocate space for elements to avoid divisions by zero. */
++  assert(size > 0);
+ 	t = (struct lh_table*)calloc(1, sizeof(struct lh_table));
+ 	if (!t)
+ 		return NULL;
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)
+ 	{
diff --git a/package/libs/libjson-c/patches/004-Issue-599-Fix-the-backwards-check-in-lh_table_insert.patch b/package/libs/libjson-c/patches/004-Issue-599-Fix-the-backwards-check-in-lh_table_insert.patch
new file mode 100644
index 0000000000..aed6918e70
--- /dev/null
+++ b/package/libs/libjson-c/patches/004-Issue-599-Fix-the-backwards-check-in-lh_table_insert.patch
@@ -0,0 +1,29 @@
+From 519dfe1591d85432986f9762d41d1a883198c157 Mon Sep 17 00:00:00 2001
+From: Eric Haszlakiewicz <erh+git@nimenees.com>
+Date: Sun, 10 May 2020 03:32:19 +0000
+Subject: [PATCH] Issue #599: Fix the backwards check in
+ lh_table_insert_w_hash() that was preventing adding more than 11 objects. Add
+ a test to check for this too.
+
+---
+ linkhash.c           |  2 +-
+ tests/test4.c        | 29 +++++++++++++++++++++++++++++
+ tests/test4.expected |  1 +
+ 3 files changed, 31 insertions(+), 1 deletion(-)
+
+diff --git a/linkhash.c b/linkhash.c
+index 51e90b1..f930efd 100644
+--- a/linkhash.c
++++ b/linkhash.c
+@@ -582,7 +582,7 @@ int lh_table_insert_w_hash(struct lh_table *t, const void *k, const void *v, con
+ 
+ 	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;
++		int new_size = (t->size > INT_MAX / 2) ? INT_MAX : (t->size * 2);
+ 		if (t->size == INT_MAX || lh_table_resize(t, new_size) != 0)
+ 			return -1;
+ 	}
+-- 
+2.26.2
+