From: Jörg Krause <joerg.krause@embedded.rocks>
Date: Sat, 12 Dec 2015 20:44:16 +0000 (+0100)
Subject: Fix data allignment issue
X-Git-Tag: 2.7.4~15^2
X-Git-Url: http://git.ipfire.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F175%2Fhead;p=thirdparty%2Fshairport-sync.git

Fix data allignment issue

Different processor targets may have different word alignment restrictions.
Typically, a two or four byte integer should start on a four-byte address in
order to be fetched correctly over a bus. An access of a misaligned memory
element may cause a bus error.

Therefore, we need to adjust the contents of a message by copying it into a new
location, before interpreting it.
---

diff --git a/rtsp.c b/rtsp.c
index 2657b4d0..d046249d 100644
--- a/rtsp.c
+++ b/rtsp.c
@@ -1085,13 +1085,16 @@ static void handle_set_parameter_metadata(rtsp_conn_info *conn, rtsp_message *re
 
   unsigned int off = 8;
 
+  uint32_t itag, vl;
   while (off < cl) {
     // pick up the metadata tag as an unsigned longint
-    uint32_t itag = ntohl(*(uint32_t *)(cp + off));
+    memcpy(&itag, (uint32_t *)(cp + off), sizeof(uint32_t)); /* can be misaligned, thus memcpy */
+    itag = ntohl(itag);
     off += sizeof(uint32_t);
 
     // pick up the length of the data
-    uint32_t vl = ntohl(*(uint32_t *)(cp + off));
+    memcpy(&vl, (uint32_t *)(cp + off), sizeof(uint32_t)); /* can be misaligned, thus memcpy */
+    vl = ntohl(vl);
     off += sizeof(uint32_t);
 
     // pass the data over