Hi Liping, On Thu, Mar 2, 2017 at 4:50 PM, Liping Zhang <zlpnobody@xxxxxxxxx> wrote: > Hi, > > 2017-03-02 15:57 GMT+08:00 <fgao@xxxxxxxxxx>: >> From: Gao Feng <fgao@xxxxxxxxxx> >> >> When h323 and sip try to insert expect nodes, they would increase >> the port by 2 for loop, and the loop condition is that "port != 0". >> So when the start port is odd number, port never increases to zero. > > This seems will never happen, since the RTP port has been ensured to > be even. > > For example, at expect_rtp_rtcp(): > ... > /* RTP port is even */ > rtp_port = port & ~htons(1); > rtcp_port = port | htons(1); > > And at set_expected_rtp_rtcp(): > ... > base_port = ntohs(tuple.dst.u.udp.port) & ~1; > rtp_port = htons(base_port); Thanks your point, I actually did not attention these codes you mentioned. But I checked the other codes, I think the dangerous may exist. The expect class is NF_CT_EXPECT_CLASS_DEFAULT, and proto is IPPROTO_UDP at the function "expect_rtp_rtcp", And it makes sure the port is even number. But look at the process_gcf, the port is got from the packet data at function get_h225_addr. So it may be odd number. It also would add one expect node whose class is NF_CT_EXPECT_CLASS_DEFAULT, and proto is IPPROTO_UDP. BTW, the loop in nat_rtp_rtcp and nat_rtp_rtcp depend on one potential condition which is protected by other functions. It doesn't seem a good style. Regards Feng -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
