udp6: Page fault panics

[Michael Butler]

On 9/17/18 4:17 AM, Andrey V. Elsukov wrote:
> On 16.09.2018 03:04, Larry Rosenman wrote:
>> vpanic() at vpanic+0x1a3/frame 0xfffffe00ca17c150
>> panic() at panic+0x43/frame 0xfffffe00ca17c1b0
>> trap_fatal() at trap_fatal+0x35f/frame 0xfffffe00ca17c200
>> trap_pfault() at trap_pfault+0x49/frame 0xfffffe00ca17c260
>> trap() at trap+0x2ba/frame 0xfffffe00ca17c370
>> calltrap() at calltrap+0x8/frame 0xfffffe00ca17c370
>> --- trap 0xc, rip = 0xffffffff80631428, rsp = 0xfffffe00ca17c440, rbp = 0xfffffe00ca17c480 ---
>> selectroute() at selectroute+0x198/frame 0xfffffe00ca17c480
>> in6_selectroute_fib() at in6_selectroute_fib+0xf/frame 0xfffffe00ca17c4a0
>> ip6_output() at ip6_output+0xfd7/frame 0xfffffe00ca17c710
> 
> (kgdb) l *selectroute+0x198
> 0xffffffff80de14c8 is in selectroute
> (/home/devel/freebsd/base/head/sys/netinet6/in6_src.c:736).
> 731		 * Use a cached route if it exists and is valid, else try to allocate
> 732		 * a new one.  Note that we should check the address family of the
> 733		 * cached destination, in case of sharing the cache with IPv4.
> 734		 */
> 735		if (ro) {
> 736			if (ro->ro_rt &&
> 737			    (!(ro->ro_rt->rt_flags & RTF_UP) ||
> 738			     ((struct sockaddr *)(&ro->ro_dst))->sa_family != AF_INET6 ||
> 739			     !IN6_ARE_ADDR_EQUAL(&satosin6(&ro->ro_dst)->sin6_addr,
> 740			     dst))) {
> 
>> calltrap() at calltrap+0x8/frame 0xfffffe00c9d863e0
>> --- trap 0xc, rip = 0xffffffff80636b2b, rsp = 0xfffffe00c9d864b0, rbp = 0xfffffe00c9d86710 ---
>> ip6_output() at ip6_output+0xeeb/frame 0xfffffe00c9d86710
>> udp6_send() at udp6_send+0x720/frame 0xfffffe00c9d868d0
> (kgdb) l *ip6_output+0xeeb
> 0xffffffff80de75bb is in ip6_output
> (/home/devel/freebsd/base/head/sys/netinet6/ip6_output.c:531).
> 526		 */
> 527		if (inp) {
> 528			ro->ro_dst.sin6_family = AF_INET6;
> 529			RT_VALIDATE((struct route *)ro, &inp->inp_rt_cookie, fibnum);
> 530		}
> 531		if (ro->ro_rt && fwd_tag == NULL && (ro->ro_rt->rt_flags & RTF_UP) &&
> 532		    ro->ro_dst.sin6_family == AF_INET6 &&
> 533		    IN6_ARE_ADDR_EQUAL(&ro->ro_dst.sin6_addr, &ip6->ip6_dst)) {
> 534			rt = ro->ro_rt;
> 535			ifp = ro->ro_rt->rt_ifp;
> 
> It looks like Ryan's assumption is correct and panics happen due to
> several threads use the same PCB and then route cache invalidation happens.
> https://lists.freebsd.org/pipermail/freebsd-net/2018-September/051563.html
> 
> But IPv6 path also needs similar patch.
> 

I can confirm that SVN r338804 resolves this issue,

	imb