libminiupnpc: add upstream security fix for CVE-2017-8798

CVE-2017-8798: Integer signedness error in MiniUPnP MiniUPnPc v1.4.20101221
through v2.0 allows remote attackers to cause a denial of service or
possibly have unspecified other impact.

For more details including a PoC, see:
https://github.com/tintinweb/pub/tree/master/pocs/cve-2017-8798

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit a0c4cf0f9698ed109b97cb1e33f4070f505e3988)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libminiupnpc/0001-miniupnpc-Fix-CVE-2017-8798.patch

@@ -0,0 +1,59 @@
+From f0f1f4b22d6a98536377a1bb07e7c20e4703d229 Mon Sep 17 00:00:00 2001
+From: Thomas Bernard <miniupnp@free.fr>
+Date: Tue, 9 May 2017 12:00:47 +0200
+Subject: [PATCH] miniupnpc: Fix CVE-2017-8798
+
+Thanks to tin/Team OSTStrom
+
+[Peter: drop Changelog.txt modification, convert to -p1 format]
+Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
+---
+ miniupnpc/miniwget.c    | 12 +++++++-----
+ 1 file changed, 9 insertions(+), 5 deletions(-)
+
+diff --git a/miniwget.c b/miniwget.c
+index 37cb47b7..1eda57c5 100644
+--- a/miniwget.c
++++ b/miniwget.c
+@@ -284,11 +284,12 @@ getHTTPResponse(int s, int * size, int * status_code)
+ 							goto end_of_stream;
+ 						}
+ 					}
+-					bytestocopy = ((int)chunksize < (n - i))?chunksize:(unsigned int)(n - i);
++					/* it is guaranteed that (n >= i) */
++					bytestocopy = (chunksize < (unsigned int)(n - i))?chunksize:(unsigned int)(n - i);
+ 					if((content_buf_used + bytestocopy) > content_buf_len)
+ 					{
+ 						char * tmp;
+-						if(content_length >= (int)(content_buf_used + bytestocopy)) {
++						if((content_length >= 0) && ((unsigned int)content_length >= (content_buf_used + bytestocopy))) {
+ 							content_buf_len = content_length;
+ 						} else {
+ 							content_buf_len = content_buf_used + bytestocopy;
+@@ -313,14 +314,15 @@ getHTTPResponse(int s, int * size, int * status_code)
+ 			{
+ 				/* not chunked */
+ 				if(content_length > 0
+-				   && (int)(content_buf_used + n) > content_length) {
++				   && (content_buf_used + n) > (unsigned int)content_length) {
+ 					/* skipping additional bytes */
+ 					n = content_length - content_buf_used;
+ 				}
+ 				if(content_buf_used + n > content_buf_len)
+ 				{
+ 					char * tmp;
+-					if(content_length >= (int)(content_buf_used + n)) {
++					if(content_length >= 0
++					   && (unsigned int)content_length >= (content_buf_used + n)) {
+ 						content_buf_len = content_length;
+ 					} else {
+ 						content_buf_len = content_buf_used + n;
+@@ -340,7 +342,7 @@ getHTTPResponse(int s, int * size, int * status_code)
+ 			}
+ 		}
+ 		/* use the Content-Length header value if available */
+-		if(content_length > 0 && (int)content_buf_used >= content_length)
++		if(content_length > 0 && content_buf_used >= (unsigned int)content_length)
+ 		{
+ #ifdef DEBUG
+ 			printf("End of HTTP content\n");