Re: kern/52353: [netbsd-8] A crash in icmpv6 code (?)

[Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>]

The following reply was made to PR kern/52353; it has been noted by GNATS.

From: Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>
To: dmb%yenn.ulegend.net@localhost
Cc: gnats-bugs%NetBSD.org@localhost, kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
        netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/52353: [netbsd-8] A crash in icmpv6 code (?)
Date: Fri, 7 Jul 2017 10:07:40 +0900

 Hi,
 
 On 2017/07/06 22:17, Dominik Bialy wrote:
 > On Tue, Jul 04, 2017 at 02:25:25PM +0900, Kengo NAKAHARA wrote:
 >> Hi,
 >>
 >> Thank you for your quick and detailed reply.
 >>
 >> On 2017/07/03 12:30, Dominik Bialy wrote:
 >>> On Sun, Jul 02, 2017 at 11:35:01PM +0000, Kengo NAKAHARA wrote:
 >>>> The following reply was made to PR kern/52353; it has been noted by GNATS.
 >>>>
 >>>> From: Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>
 >>>> To: gnats-bugs%NetBSD.org@localhost, kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
 >>>>         netbsd-bugs%netbsd.org@localhost
 >>>> Cc: 
 >>>> Subject: Re: kern/52353: [netbsd-8] A crash in icmpv6 code (?)
 >>>> Date: Mon, 3 Jul 2017 08:33:32 +0900
 >>>>
 >>>>  Hi,
 >>>>  
 >>>>  On 2017/07/01 22:40, dmb%yenn.ulegend.net@localhost wrote:
 >>>>  > System: NetBSD yenn 8.0_BETA NetBSD 8.0_BETA (YENN) #6: Mon Jun 26 08:49:07 UTC 2017 builds@yenn:/var/obj/sys/arch/amd64/compile/YENN amd64
 >>>>  
 >>>>  It seems you use other than GENERIC kernel config.Could you show your
 >>>>  kernel config?
 >>>>  
 >>> It is almost GENERIC with: GATEWAY, and altq* options added.  The setup
 >>> is somewhat unusual, since I'm using ipf+pf+the old altq
 >>>
 >>> Here's the config:
 >>>
 >>> http://yenn.ulegend.net/~dmb/YENN
 >>>
 >>> Here's dmesg.boot:
 >>>
 >>> http://yenn.ulegend.net/~dmb/dmesg.boot
 >>>
 >>> (The panic in this dmesg is probably unrelated.)
 >>>
 >>> In altq I'm using WFQ over a 0.75 Mbps uplink.
 >>>
 >>>>  > Architecture: x86_64
 >>>>  > Machine: amd64
 >>>>  >> Description:
 >>>>  > yenn# crash -M netbsd.3.core -N netbsd.3
 >>>>  > Crash version 8.0_BETA, image version 8.0_BETA.
 >>>>  > System panicked: in6_cksum: mbuf too short for IPv6 header
 >>>>  > Backtrace from time of crash is available.
 >>>>  > crash> bt
 >>>>  > _KERNEL_OPT_NARCNET() at 0
 >>>>  > ?() at fffffe80a11bcc00
 >>>>  > vpanic() at vpanic+0x149
 >>>>  > snprintf() at snprintf
 >>>>  > in6_cksum() at in6_cksum+0x1a2
 >>>>  > _icmp6_input() at _icmp6_input+0xb4
 >>>>  > wqinput_work() at wqinput_work+0x88
 >>>>  > workqueue_worker() at workqueue_worker+0xbc
 >>>>  > 
 >>>>  > yes, IPv6 is via gif(4), but _before_ the patch for MP-fy
 >>>>  >> How-To-Repeat:
 >>>>  > 	possibly ping the machine for some time (?) with IPv6 on a gif(4) (?)
 >>>>  
 >>>>  Which do you use IPv6 over IPv6 or IPv6 over IPv4?
 >>>>  
 >>> IPv6 over IPv4 -- he.net tunnelbroker
 >>
 >> Hmm, I guess there may be the issue in combination ALTQ and gif(4).
 >> So, I try to reproduce it in my simple environment. That is,
 >>     - use two NetBSD-8 machine and connect directly their ethernet ports
 >>     - create IPv6 over IPv4 gif(4) between the two machines
 >>     - apply below WFQ to the gif(4) psrc, pdst ethernet
 >>       ====================
 >>       interface wm2 bandwidth 750000 wfq
 >>       ====================
 >>     - ping6 over gif(4) each other
 >> However, I cannot reproduce it yet...
 >>
 >> By the way, ozaki-r@n.o help me to research this issue. He also implements
 >> a patch. Could you try below patch?
 >> ====================
 >> diff --git a/sys/netinet6/icmp6.c b/sys/netinet6/icmp6.c
 >> index f740932036d..3b45ba8d785 100644
 >> --- a/sys/netinet6/icmp6.c
 >> +++ b/sys/netinet6/icmp6.c
 >> @@ -494,6 +494,15 @@ _icmp6_input(struct mbuf *m, int off, int proto)
 >>  		goto freeit;
 >>  	}
 >>  
 >> +	if (m->m_len < sizeof(struct ip6_hdr)) {
 >> +		m = m_pullup(m, sizeof(struct ip6_hdr));
 >> +		if (m == NULL) {
 >> +			ICMP6_STATINC(ICMP6_STAT_TOOSHORT);
 >> +			icmp6_ifstat_inc(rcvif, ifs6_in_error);
 >> +			goto freeit;
 >> +		}
 >> +	}
 >> +
 >>  	ip6 = mtod(m, struct ip6_hdr *);
 >>  	IP6_EXTHDR_GET(icmp6, struct icmp6_hdr *, m, off, sizeof(*icmp6));
 >>  	if (icmp6 == NULL) {
 >> ====================
 >>
 >> If the issue is reproduced after applying above patch, could you tell
 >> me your detailed network configuration and ipf/pf setting? 
 >> Of course, within the range you can show with no problem.
 >>
 > OK, then I applied the patch, and I'm pinging the machine
 > for quite some time.  The uptime is almost 2 days.
 
 Thank you for your testing! I committed above patch to -current branch,
 and sent pullup request to -8 branch. It will merge to -8 branch soon. 
 
 > Close the PR?  When it'd be needed it could be reopened again, no?
 
 Ok, I close this PR.
 
 
 Thanks,
 
 -- 
 //////////////////////////////////////////////////////////////////////
 Internet Initiative Japan Inc.
 
 Device Engineering Section,
 IoT Platform Development Department,
 Network Division,
 Technology Unit
 
 Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>