Re: kern/51522

[Tom Ivar Helbekkmo <tih%hamartun.priv.no@localhost>]

The following reply was made to PR kern/51522; it has been noted by GNATS.

From: Tom Ivar Helbekkmo <tih%hamartun.priv.no@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/51522
Date: Tue, 18 Oct 2016 18:33:51 +0200

 Hitting the latest crash with gdb, I find that it's the call at the very
 bottom of icmp_error(), in sys/netinet/ip_icmp.c, that fails, i.e. the
 
 freeit:
         m_freem(n);
 
 icmp_error() was called from near the bottom of udp_input(), in
 sys/netinet/udp_usrreq.c:
 
         if (n == 0) {
 [...]
                 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_PORT, 0, 0);
                 m = NULL;
         }
 
 (Thus, the 'm' in the latter is the 'n' in the former.)
 
 The backtrace, in gdb, looks like this:
 
 #0  0xffffffff80119ab5 in cpu_reboot (howto=howto@entry=260, bootstr=bootstr@entry=0x0)
     at /usr/src/sys/arch/amd64/amd64/machdep.c:676
 #1  0xffffffff808ad94c in vpanic (fmt=0xffffffff80ed4ad0 "kernel %sassertion \"%s\" failed: file \"%s\", line %d ", 
     ap=ap@entry=0xfffffe8100007d08) at /usr/src/sys/kern/subr_prf.c:342
 #2  0xffffffff80beee75 in kern_assert (
     fmt=fmt@entry=0xffffffff80ed4ad0 "kernel %sassertion \"%s\" failed: file \"%s\", line %d ")
     at /usr/src/sys/lib/libkern/kern_assert.c:51
 #3  0xffffffff808d85f8 in m__freem (f=f@entry=0xffffffff80e50400 <__func__.10240> "m_freem", l=l@entry=1990, 
     m=0xffff80001090d410, m@entry=0xfffffe80560c3600) at /usr/src/sys/kern/uipc_mbuf.c:1972
 #4  0xffffffff808d9644 in m_freem (m=m@entry=0xfffffe80560c3600) at /usr/src/sys/kern/uipc_mbuf.c:1990
 #5  0xffffffff8057ef24 in icmp_error (n=n@entry=0xfffffe80560c3600, type=type@entry=3, code=<optimized out>, 
     code@entry=3, dest=4294967295, dest@entry=0, destmtu=destmtu@entry=0) at /usr/src/sys/netinet/ip_icmp.c:363
 #6  0xffffffff8059fbcf in udp_input (m=0xfffffe80560c3600) at /usr/src/sys/netinet/udp_usrreq.c:436
 #7  0xffffffff80580fde in ip_input (m=0xfffffe80560c3600) at /usr/src/sys/netinet/ip_input.c:846
 #8  ipintr (arg=<optimized out>) at /usr/src/sys/netinet/ip_input.c:442
 #9  0xffffffff8088560d in softint_execute (l=<optimized out>, s=4, si=0xffff80008f9c3230)
     at /usr/src/sys/kern/kern_softint.c:589
 #10 softint_dispatch (pinned=<optimized out>, s=4) at /usr/src/sys/kern/kern_softint.c:871
 #11 0xffffffff8011419f in Xsoftintr ()