>Number: 153841
>Category: kern
>Synopsis: page fault in icmp6_error2() called from nd6_llinfo_timer()
>Confidential: no
>Severity: critical
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Mon Jan 10 12:50:07 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator: Petr Lampa
>Release: 8.2-PRERELEASE
>Organization:
BUT brno
>Environment:
FreeBSD xxx 8.2-PRERELEASE FreeBSD 8.2-PRERELEASE #16: Tue Nov 30 12:44:18 CET
2010 r...@xxxx:/usr/src/sys/i386/compile/GUTA i386
>Description:
page fault
Stopped at icmp6_error2+0xc3: movl 0x1dc(%eax),%eax
where:
Tracing pid 11 tid 1000006 td 0xc851e000
icmp6_error2(cad86800,1,3,0,c86d4c00,...) at icmp6_error2+0xc3
nd6_llinfo_timer(cc7da400,c851e000,c838bc40,c851e870,c851e000,...) at
timer+0x126
softclock(c07bd760,c851e000,0,109,3b7b822b,...) at softclock_0x22a
icmp6_error2+0xa3: jmp icmp6_error2+0x136
icmp6_error2+0xa8: cmpl $0x27,0xc(%ebx)
icmp6_error2+0xac: jnbe icmp6_error2+0xe0
icmp6_error2+0xae: addl $0x1,ip6stat+0x8
icmp6_error2+0xb5: adcl $0,ip6stat+0xc
icmp6_error2+0xbc: movl 0x18(%ebx),%eax
icmp6_error2+0xbf: testl %eax,%eax
icmp6_error2+0xc1: jz icmp6_error2+0xd3
icmp6_error2+0xc3: movl 0x1dc(%eax),%eax
icmp6_error2+0xc9: movl 0(%eax),%eax
icmp6_error2+0xcb: addl $0x1,0x30(%eax)
icmp6_error2+0xcf: adcl $0,0x34(%eax)
icmp6_error2+0xd3: movl %ebx,0(%esp)
icmp6_error2+0xd6: call m_freem
icmp6_error2+0xdb: jmp icmp6_error2+0x136
icmp6_error2+0xdd: leal 0(%esi),%esi
icmp6_error2+0xe0: movl 0x8(%ebx),%esi
icmp6_error2+0xe3: movl $0,0x8(%esp)
icmp6_error2+0xeb: movl %edi,0x4(%esp)
icmp6_error2+0xef: leal 0x8(%esi),%eax
icmp6_error2+0xf2: movl ieax,0(%esp)
icmp6_error2+0xf5: call in6_setscope
icmp6_error2+0xfa: testl %eax,%eax
icmp6_error2+0xfc: jnz icmp6_error2+0x136
(sorry, if there is some garbage here, this is a result of ocr)
So, the location of page fault corresponds to the last branch of
IP6_EXTHDR_CHECK() macro expanded in icmp6_error2:
if ((m)->m_len < (off) + (hlen)) { \
V_ip6stat.ip6s_tooshort++; \
in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated); \
The content of mbuf (m) is:
0xcad86800: 0 0 cad86896 1e
0xcad86810: 0 1 0 0
0xcad86820: 5a 0 4 6
0xcad86830: 0 0 5e0000 30000
It seems, that pkthdr is not there and so m->m_pkthdr.rcvif is 0 and it's
dereferenced without a check.
>How-To-Repeat:
It happened after ping6/traceroute6 (not sure) to unresponding IPv6 address,
which after time started responding (probably, I'm not really sure).
>Fix:
check flags for M_PKTHDR in IP6_EXTHDR_CHECK()
>Release-Note:
>Audit-Trail:
>Unformatted:
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