libubox: backport security patches

This backports some security relevant patches from libubox master. These
patches should not change the existing API and ABI so that old
applications still work like before without any recompilation.
Application can now also use more secure APIs.

The new more secure interfaces are also available, but not used.

OpenWrt master and 19.07 already have these patches by using a more
recent libubox version.

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

1 files changed, 78 insertions, 0 deletions

diff --git a/package/libs/libubox/patches/0004-blob-introduce-blob_parse_untrusted.patch b/package/libs/libubox/patches/0004-blob-introduce-blob_parse_untrusted.patch
new file mode 100644
index 0000000000..b624db2cfe
--- /dev/null
+++ b/package/libs/libubox/patches/0004-blob-introduce-blob_parse_untrusted.patch
@@ -0,0 +1,78 @@
+From b6a0a070f2e14808e835c2fcfa3820a55041902f Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Petr=20=C5=A0tetiar?= <ynezz@true.cz>
+Date: Mon, 9 Dec 2019 14:11:45 +0100
+Subject: blob: introduce blob_parse_untrusted
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+blob_parse can be only used on trusted input as it has no possibility to
+check the length of the provided input buffer, which might lead to
+undefined behaviour and/or crashes when supplied with malformed,
+corrupted or otherwise specially crafted input.
+
+So this introduces blob_parse_untrusted variant which expects additional
+input buffer length argument and thus should be able to process also
+inputs from untrusted sources.
+
+Signed-off-by: Petr Štetiar <ynezz@true.cz>
+---
+ blob.c | 24 ++++++++++++++++++++++++
+ blob.h |  7 +++++++
+ 2 files changed, 31 insertions(+)
+
+--- a/blob.c
++++ b/blob.c
+@@ -253,6 +253,30 @@ blob_parse_attr(struct blob_attr *attr,
+ }
+ 
+ int
++blob_parse_untrusted(struct blob_attr *attr, size_t attr_len, struct blob_attr **data, const struct blob_attr_info *info, int max)
++{
++	struct blob_attr *pos;
++	size_t len = 0;
++	int found = 0;
++	size_t rem;
++
++	if (!attr || attr_len < sizeof(struct blob_attr))
++		return 0;
++
++	len = blob_raw_len(attr);
++	if (len != attr_len)
++		return 0;
++
++	memset(data, 0, sizeof(struct blob_attr *) * max);
++	blob_for_each_attr_len(pos, attr, len, rem) {
++		found += blob_parse_attr(pos, rem, data, info, max);
++	}
++
++	return found;
++}
++
++/* use only on trusted input, otherwise consider blob_parse_untrusted */
++int
+ blob_parse(struct blob_attr *attr, struct blob_attr **data, const struct blob_attr_info *info, int max)
+ {
+ 	struct blob_attr *pos;
+--- a/blob.h
++++ b/blob.h
+@@ -199,6 +199,7 @@ extern void blob_nest_end(struct blob_bu
+ extern struct blob_attr *blob_put(struct blob_buf *buf, int id, const void *ptr, unsigned int len);
+ extern bool blob_check_type(const void *ptr, unsigned int len, int type);
+ extern int blob_parse(struct blob_attr *attr, struct blob_attr **data, const struct blob_attr_info *info, int max);
++extern int blob_parse_untrusted(struct blob_attr *attr, size_t attr_len, struct blob_attr **data, const struct blob_attr_info *info, int max);
+ extern struct blob_attr *blob_memdup(struct blob_attr *attr);
+ extern struct blob_attr *blob_put_raw(struct blob_buf *buf, const void *ptr, unsigned int len);
+ 
+@@ -254,5 +255,11 @@ blob_put_u64(struct blob_buf *buf, int i
+ 	     (blob_pad_len(pos) >= sizeof(struct blob_attr)); \
+ 	     rem -= blob_pad_len(pos), pos = blob_next(pos))
+ 
++#define blob_for_each_attr_len(pos, attr, attr_len, rem) \
++	for (rem = attr ? blob_len(attr) : 0, \
++	     pos = (struct blob_attr *) (attr ? blob_data(attr) : NULL); \
++	     rem >= sizeof(struct blob_attr) && rem < attr_len && (blob_pad_len(pos) <= rem) && \
++	     (blob_pad_len(pos) >= sizeof(struct blob_attr)); \
++	     rem -= blob_pad_len(pos), pos = blob_next(pos))
+ 
+ #endif