kern/113359: panic sbdrop after ICMP6, packet too big

[Frank Behrens]

>Number:         113359
>Category:       kern
>Synopsis:       panic sbdrop after ICMP6, packet too big
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Jun 05 09:10:12 GMT 2007
>Closed-Date:
>Last-Modified:
>Originator:     Frank Behrens
>Release:        FreeBSD 6.2-STABLE-200705211513 i386
>Organization:
>Environment:
System: FreeBSD moon.behrens 6.2-STABLE-200705211513 FreeBSD 6.2-STABLE-200705211513 #0: Tue Jun 5 09:07:43 CEST 2007 
Custom kernel, Network Options:
options         SMP

options         INET                    # InterNETworking
options         INET6                   # IPv6 communications protocols

options         IPSEC                   #IP security
options         IPSEC_ESP               #IP security (crypto; define w/ IPSEC)
options         IPSEC_DEBUG             #debug for IP security

Outgoing interface: tun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1456


>Description:
The machine panics with "sbdrop" after receiving ICMP6, packet to big.

ping6 -m -v -b 8000 -c 1 -s 1408 2a01:xxxx::xxxx
PING6(1456=40+8+1408 bytes) 2a01:yyyy::yyyy --> 2a01:xxxx::xxxx
new path MTU (1440) is notified

The exchanged packets are:
09:57:30.358528 IP6 (hlim 64, next-header: ICMPv6 (58), length: 1416) host > remote: [icmp6 sum ok] ICMP6, echo request, length 1416, seq 0
09:57:30.491101 IP6 (hlim 61, next-header: ICMPv6 (58), length: 1240) router > host: [icmp6 sum ok] ICMP6, packet too big, length 1240, mtu 1440

The panic is:
(kgdb) bt
#0  doadump () at pcpu.h:165
#1  0xc0525da1 in boot (howto=260) at /data3/sources/fbsd6/sys/kern/kern_shutdown.c:409
#2  0xc052649b in panic (fmt=0xc075c5ba "sbdrop") at /data3/sources/fbsd6/sys/kern/kern_shutdown.c:565
#3  0xc056dd40 in sbdrop_locked (sb=0xed1ba818, len=1316) at /data3/sources/fbsd6/sys/kern/uipc_socket2.c:1103
#4  0xc056ecf8 in sbflush_locked (sb=0xed1ba818) at /data3/sources/fbsd6/sys/kern/uipc_socket2.c:1070
#5  0xc056ed4d in sbrelease_locked (sb=0xed1ba818, so=0x0) at /data3/sources/fbsd6/sys/kern/uipc_socket2.c:569
#6  0xc056f502 in sbrelease (sb=0xed1ba818, so=0x0) at /data3/sources/fbsd6/sys/kern/uipc_socket2.c:582
#7  0xc056b838 in sorflush (so=0xc40cf590) at /data3/sources/fbsd6/sys/kern/uipc_socket.c:1502
#8  0xc056bb20 in sofree (so=0xc40cf590) at /data3/sources/fbsd6/sys/kern/uipc_socket.c:413
#9  0xc056c1e3 in soclose (so=0xc40cf590) at /data3/sources/fbsd6/sys/kern/uipc_socket.c:491
#10 0xc05576d9 in soo_close (fp=0xc3fd55e8, td=0xc3cb3c00) at /data3/sources/fbsd6/sys/kern/sys_socket.c:317
#11 0xc04f86b7 in fdrop_locked (fp=0xc3fd55e8, td=0xc3cb3c00) at file.h:296
#12 0xc04f8b76 in closef (fp=0xc3fd55e8, td=0xc3cb3c00) at /data3/sources/fbsd6/sys/kern/kern_descrip.c:1954
#13 0xc04fa7d5 in fdfree (td=0xc3cb3c00) at /data3/sources/fbsd6/sys/kern/kern_descrip.c:1639
#14 0xc0505d43 in exit1 (td=0xc3cb3c00) at /data3/sources/fbsd6/sys/kern/kern_exit.c:273
#15 0xc052a416 in sigexit (td=0xc3cb3c00, sig=2) at /data3/sources/fbsd6/sys/kern/kern_sig.c:2459
#16 0xc052b10f in postsig (sig=2) at /data3/sources/fbsd6/sys/kern/kern_sig.c:2340
#17 0xc054d4b6 in ast (framep=0xed1bad38) at /data3/sources/fbsd6/sys/kern/subr_trap.c:270
#18 0xc06fd17d in doreti_ast () at /data3/sources/fbsd6/sys/i386/i386/exception.s:293
#19 0xed1bad38 in ?? ()
#20 0x0000003b in ?? ()
#21 0x0000003b in ?? ()
#22 0x0000003b in ?? ()
#23 0xbfbfe6e0 in ?? ()
#24 0xbfbfeaf0 in ?? ()
#25 0xbfbfe2e8 in ?? ()
#26 0xed1bad64 in ?? ()
#27 0xbfbfe6b0 in ?? ()
#28 0x00000c31 in ?? ()
#29 0x00000002 in ?? ()
#30 0x00000000 in ?? ()
#31 0x00000000 in ?? ()
#32 0x00000002 in ?? ()
#33 0x28175e03 in ?? ()
#34 0x00000033 in ?? ()
#35 0x00000202 in ?? ()
#36 0xbfbfe2dc in ?? ()
#37 0x0000003b in ?? ()
#38 0x00000000 in ?? ()
#39 0x00000000 in ?? ()
#40 0x00000000 in ?? ()
#41 0x00000000 in ?? ()
#42 0x35aab000 in ?? ()
#43 0xc3cb1c90 in ?? ()
#44 0xc3cb3c00 in ?? ()
#45 0xed1ba6ac in ?? ()
#46 0xed1ba694 in ?? ()
#47 0xc34e8a80 in ?? ()
#48 0xc053b8ef in sched_switch (td=0xbfbfeaf0, newtd=0xbfbfe6b0, flags=Cannot access memory at address 0xbfbfe2f8
) at /data3/sources/fbsd6/sys/kern/sched_4bsd.c:973
Previous frame inner to this frame (corrupt stack?)
(kgdb) up
#1  0xc0525da1 in boot (howto=260) at /data3/sources/fbsd6/sys/kern/kern_shutdown.c:409
409                     doadump();
(kgdb) up
#2  0xc052649b in panic (fmt=0xc075c5ba "sbdrop") at /data3/sources/fbsd6/sys/kern/kern_shutdown.c:565
565             boot(bootopt);
(kgdb) up
#3  0xc056dd40 in sbdrop_locked (sb=0xed1ba818, len=1316) at /data3/sources/fbsd6/sys/kern/uipc_socket2.c:1103
1103                                    panic("sbdrop");
(kgdb) print *sb
$1 = {sb_sel = {si_thrlist = {tqe_next = 0x0, tqe_prev = 0x0}, si_thread = 0x0, si_note = {kl_list = {slh_first = 0x0},
      kl_lock = 0, kl_unlock = 0, kl_locked = 0, kl_lockarg = 0x0}, si_flags = 0}, sb_mtx = {mtx_object = {lo_class = 0xc078e8a0,
      lo_name = 0xc075c534 "so_rcv", lo_type = 0xc075c534 "so_rcv", lo_flags = 196608, lo_list = {tqe_next = 0x0, tqe_prev = 0x0},
      lo_witness = 0x0}, mtx_lock = 3284876288, mtx_recurse = 0}, sb_state = 0, sb_mb = 0x0, sb_mbtail = 0x0, sb_lastrecord = 0x0,
  sb_cc = 1316, sb_hiwat = 8000, sb_mbcnt = 3072, sb_mbmax = 64000, sb_ctl = 76, sb_lowat = 1, sb_timeo = 0, sb_flags = 64}
(kgdb)


>How-To-Repeat:
ping6(8) to a host, where you get an "ICMP6, packet to big" answer.


>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted: