BUG/MAJOR: fcgi: Fix uninitialized reserved bytes

The output buffer is not zero-initialized. If we don't clear reserved
bytes, fcgi requests sent to backend will leak sensitive data.

This patch must be backported as far as 2.2.

(cherry picked from commit 2e6bf0a2722866ae0128a4392fa2375bd1f03ff8)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit db03179fee55c60a92ce6b86a0f04dbb9ba0328b)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit f988992d16f45ef03d5bbb024a1042ed8123e4c5)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 0dc4cdc276d4a0e3347b7c3c4aedca2a2e0ab428)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/src/fcgi.c b/src/fcgi.c
index 1c2543d..778ce9e 100644
--- a/src/fcgi.c
+++ b/src/fcgi.c
@@ -47,7 +47,7 @@
 	out->area[len++] = ((h->len >> 8) & 0xff);
 	out->area[len++] = (h->len & 0xff);
 	out->area[len++] = h->padding;
-	len++; /* rsv */
+	out->area[len++] = 0; /* rsv */
 
 	out->data = len;
 	return 1;
@@ -94,7 +94,11 @@
 	out->area[len++] = ((r->role >> 8) & 0xff);
 	out->area[len++] = (r->role & 0xff);
 	out->area[len++] = r->flags;
-	len += 5; /* rsv */
+	out->area[len++] = 0; /* rsv */
+	out->area[len++] = 0;
+	out->area[len++] = 0;
+	out->area[len++] = 0;
+	out->area[len++] = 0;
 
 	out->data = len;
 	return 1;