[openbsc 1/2] rtp_proxy: Prevent out-of-bounds read in rtcp_sdes_cname_mangle

[Daniel Willmann]

In rtcp_sdes_cname_mangle when skipping over additional zeroes at the
end of a chunk we should not read past the actual message (rtcp_end).

Fixes CID #1206579
---
 openbsc/src/libtrau/rtp_proxy.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/openbsc/src/libtrau/rtp_proxy.c b/openbsc/src/libtrau/rtp_proxy.c
index 122daf2..1567323 100644
--- a/openbsc/src/libtrau/rtp_proxy.c
+++ b/openbsc/src/libtrau/rtp_proxy.c
@@ -374,7 +374,7 @@ static int rtcp_sdes_cname_mangle(struct msgb *msg, struct 
rtcp_hdr *rh,
                        tag = *cur++;
                        if (tag == 0) {
                                /* end of chunk, skip additional zero */
-                               while (*cur++ == 0) { }
+                               while ((*cur++ == 0) && (cur < rtcp_end)) { }
                                break;
                        }
                        len = *cur++;
-- 
1.8.4.2