On May 22, 2024, at 12:17 PM, Bjoern A. Zeeb <bzeeb-lists@lists.zabbadoz.net> wrote:

Hi,
sorry, I cannot dump; this is a diskless and = netdump does not do IPv6;
needless to say that would be = funny in this case anyway; unfortunately
I have also = already re-compiled the kernel so I can only look things up approx.

FreeBSD main from May 13 = (f3eeeb959c9b00c89a2e1ff009c78162eb398656).

I= assume we lost the ifp from a destroy of a cloned interface in = ip6_output()
between lines 806 and 811?

Kernel page fault with the following = non-sleepable locks held:
exclusive rw rawinp (rawinp) r =3D= 0 (0xfffff80002a6e1a0) locked @ /usr/src/sys/netinet6/raw_ip6.c:393
stack backtrace:
#0 0xffffffff80bb679c at = witness_debugger+0x6c
#1 0xffffffff80bb7979 at = witness_warn+0x3e9
#2 0xffffffff81061d10 at = trap_pfault+0x80
#3 0xffffffff81033878 at calltrap+0x8
#4 0xffffffff80d99228 at rip6_send+0x5a8
#5 = 0xffffffff80bf570e at sosend_generic+0x5ee
#6 = 0xffffffff80bf5c49 at sousrsend+0x79
#7 0xffffffff80bfbd5c = at kern_sendit+0x1bc
#8 0xffffffff80bfc073 at = sendit+0x1b3
#9 0xffffffff80bfc1ab at sys_sendmsg+0x5b
#10 0xffffffff81062638 at amd64_syscall+0x158
#11= 0xffffffff8103418b at fast_syscall_common+0xf8
Created = wlan(4) interfaces: wlan

Note the creation of wlan, and a following ICMP6 = (ping6) packet.

Fatal trap 12: page fault = while in kernel mode
cpuid =3D 2; apic id =3D 02
fault virtual address   =3D 0x0
30.
fault code =             &n= bsp;=3D supervisor read data, page not present
instruction = pointer     =3D 0x20:0xffffffff80d821bd
stack pointer =           =3D = 0x28:0xfffffe00468ba850
frame pointer =           =3D = 0x28:0xfffffe00468baa00
code segment =            =3D = base 0x0, limit 0xfffff, type 0x1b
=             &n= bsp;          =3D DPL = 0, pres 1, long 1, def32 0, gran 1
processor eflags =        =3D interrupt enabled, resume, = IOPL =3D 0
current process =         =3D 1073 (ping6)
rdi: ffffffff81be2c00 rsi: fffffe00468ba884 rdx: = 00000000030002ff
rcx: 0000000000001c1c r8: = 0000000000000028 r9: 0000000000000003
rax: = 0000000000000000 rbx: 0000000000000000 rbp: fffffe00468baa00
r10: 000000000000aa01 r11: 00000000000000ff r12: = fffff800017d3000
r13: fffff8000286df20 r14: = 0000000000000000 r15: fffff80001f1059c
trap number =             =3D= 12
panic: page fault
cpuid =3D 2
time =3D 1716352160
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame = 0xfffffe00468ba520
vpanic() at vpanic+0x13f/frame = 0xfffffe00468ba650
panic() at panic+0x43/frame = 0xfffffe00468ba6b0
trap_fatal() at trap_fatal+0x40b/frame = 0xfffffe00468ba710
trap_pfault() at trap_pfault+0xa0/frame = 0xfffffe00468ba780
calltrap() at calltrap+0x8/frame = 0xfffffe00468ba780
--- trap 0xc, rip =3D = 0xffffffff80d821bd, rsp =3D 0xfffffe00468ba850, rbp =3D = 0xfffffe00468baa00 ---
ip6_output() at = ip6_output+0xb5d/frame 0xfffffe00468baa00
rip6_send() at = rip6_send+0x5a8/frame 0xfffffe00468babb0
sosend_generic() = at sosend_generic+0x5ee/frame 0xfffffe00468bac60
sousrsend()= at sousrsend+0x79/frame 0xfffffe00468bacc0
kern_sendit() = at kern_sendit+0x1bc/frame 0xfffffe00468bad50
sendit() at = sendit+0x1b3/frame 0xfffffe00468bada0
sys_sendmsg() at = sys_sendmsg+0x5b/frame 0xfffffe00468bae00
amd64_syscall() = at amd64_syscall+0x158/frame 0xfffffe00468baf30
fast_syscall_common() at fast_syscall_common+0xf8/frame = 0xfffffe00468baf30
--- syscall (28, FreeBSD ELF64, = sendmsg), rip =3D 0x2959dfacc85a, rsp =3D 0x2959dae92668, rbp =3D = 0x2959dae926c0 ---
KDB: enter: panic
[ = thread pid 1073 tid 100157 ]
Stopped at =      kdb_enter+0x33: movq =    $0,0x10544e2(%rip)

(lldb) image lookup -v --address rip6_send+0x5a8
=      Address: kernel.full[0xffffffff80d99228] = (kernel.full.PT_LOAD[1]..text + 10572328)
=      Summary: kernel.full`rip6_send + 1448 at = raw_ip6.c:533:10
=       Module: file =3D = "/usr/obj/usr/src/amd64.amd64/sys/GENERIC/kernel.full", arch =3D = "x86_64"
CompileUnit: id =3D {0x000005ba}, file =3D = "/usr/src/sys/netinet6/raw_ip6.c", language =3D "c99"
=     Function: id =3D {0x023e5ddd}, name =3D = "rip6_send", range =3D [0xffffffff80d98c80-0xffffffff80d9973d)
    FuncType: id =3D {0x023e5ddd}, = byte-size =3D 0, decl =3D raw_ip6.c:338, compiler_type =3D "int (struct = socket *, int, struct mbuf *, struct sockaddr *, struct mbuf *, struct = thread *)"
      Blocks: id = =3D {0x023e5ddd}, range =3D [0xffffffff80d98c80-0xffffffff80d9973d)
   LineEntry: = [0xffffffff80d99211-0xffffffff80d9922a): = /usr/src/sys/netinet6/raw_ip6.c:533:10
=       Symbol: id =3D {0x0000840a}, range =3D= [0xffffffff80d98c80-0xffffffff80d9973d), name=3D"rip6_send"
    Variable: id =3D {0x023e5df7}, name = =3D "so", type =3D "socket *", valid ranges =3D <block>, location = =3D [0xffffffff80d990c0, 0xffffffff80d99398) -> DW_OP_breg6 RBP-168, = decl =3D raw_ip6.c:338
    Variable: = id =3D {0x023e5e07}, name =3D "flags", type =3D "int", valid ranges =3D = <block>, location =3D <empty>, decl =3D raw_ip6.c:338
    Variable: id =3D {0x023e5e13}, name = =3D "m", type =3D "mbuf *", valid ranges =3D <block>, location =3D = [0xffffffff80d990c0, 0xffffffff80d99398) -> DW_OP_reg12 R12, decl =3D = raw_ip6.c:338
    Variable: id =3D = {0x023e5e23}, name =3D "nam", type =3D "sockaddr *", valid ranges =3D = <block>, location =3D [0xffffffff80d98e48, 0xffffffff80d99398) = -> DW_OP_GNU_entry_value(DW_OP_reg2 RCX), DW_OP_stack_value, decl =3D = raw_ip6.c:338
    Variable: id =3D = {0x023e5e33}, name =3D "control", type =3D "mbuf *", valid ranges =3D = <block>, location =3D [0xffffffff80d990c0, 0xffffffff80d99398) = -> DW_OP_breg6 RBP-48, decl =3D raw_ip6.c:339
=     Variable: id =3D {0x023e5e43}, name =3D "td", = type =3D "thread *", valid ranges =3D <block>, location =3D = <empty>, decl =3D raw_ip6.c:339
=     Variable: id =3D {0x023e5e4f}, name =3D "et", = type =3D "epoch_tracker", valid ranges =3D <block>, location =3D = DW_OP_fbreg -200, decl =3D raw_ip6.c:341
=     Variable: id =3D {0x023e5e5f}, name =3D "opt", = type =3D "ip6_pktopts", valid ranges =3D <block>, location =3D = DW_OP_fbreg -408, decl =3D raw_ip6.c:347
=     Variable: id =3D {0x023e5e6f}, name =3D "oifp", = type =3D "ifnet *", valid ranges =3D <block>, location =3D = DW_OP_fbreg -56, decl =3D raw_ip6.c:348
=     Variable: id =3D {0x023e5e7e}, name =3D "hlim", = type =3D "int", valid ranges =3D <block>, location =3D DW_OP_fbreg = -80, decl =3D raw_ip6.c:353
=     Variable: id =3D {0x023e5e8e}, name =3D "in6a", = type =3D "in6_addr", valid ranges =3D <block>, location =3D = DW_OP_fbreg -120, decl =3D raw_ip6.c:354
=     Variable: id =3D {0x023e5ebe}, name =3D "type", = type =3D "int", valid ranges =3D <block>, location =3D = [0xffffffff80d990c0, 0xffffffff80d99398) -> DW_OP_breg6 RBP-72, decl = =3D raw_ip6.c:350
    Variable: id =3D = {0x023e5ece}, name =3D "code", type =3D "int", valid ranges =3D = <block>, location =3D [0xffffffff80d990c0, 0xffffffff80d99398) = -> DW_OP_breg6 RBP-76, decl =3D raw_ip6.c:350
=     Variable: id =3D {0x023e5ede}, name =3D = "scope_ambiguous", type =3D "int", valid ranges =3D <block>, = location =3D [0xffffffff80d990c0, 0xffffffff80d99398) -> DW_OP_breg6 = RBP-92, decl =3D raw_ip6.c:351
=     Variable: id =3D {0x023e5efe}, name =3D "inp", = type =3D "inpcb *", valid ranges =3D <block>, location =3D = [0xffffffff80d98cb4, 0xffffffff80d9973d) -> DW_OP_breg6 RBP-64, decl = =3D raw_ip6.c:342
    Variable: id =3D = {0x023e5f0e}, name =3D "error", type =3D "int", valid ranges =3D = <block>, location =3D [0xffffffff80d991a9, 0xffffffff80d9922a) = -> DW_OP_consts +0, DW_OP_stack_value, decl =3D raw_ip6.c:349
    Variable: id =3D {0x023e5f2e}, name = =3D "optp", type =3D "ip6_pktopts *", valid ranges =3D <block>, = location =3D [0xffffffff80d99183, 0xffffffff80d9922a) -> DW_OP_reg3 = RBX, decl =3D raw_ip6.c:347
=     Variable: id =3D {0x023e5f3e}, name =3D "ip6", = type =3D "ip6_hdr *", valid ranges =3D <block>, location =3D = [0xffffffff80d990c0, 0xffffffff80d99398) -> DW_OP_breg6 RBP-160, decl = =3D raw_ip6.c:345

   532 =         NET_EPOCH_ENTER(et);
   533 =         error =3D ip6_output(m, = optp, NULL, 0, inp->in6p_moptions, &oifp, inp);
=    534 =         NET_EPOCH_EXIT(et);

(lldb) image lookup -v = --address ip6_output+0xb5d
=      Address: kernel.full[0xffffffff80d821bd] = (kernel.full.PT_LOAD[1]..text + 10478013)
=      Summary: kernel.full`ip6_output + 2909 at = ip6_output.c:811:3
=       Module: file =3D = "/usr/obj/usr/src/amd64.amd64/sys/GENERIC/kernel.full", arch =3D = "x86_64"
CompileUnit: id =3D {0x000005b5}, file =3D = "/usr/src/sys/netinet6/ip6_output.c", language =3D "c99"
=     Function: id =3D {0x023ab5ce}, name =3D = "ip6_output", range =3D [0xffffffff80d81660-0xffffffff80d838c4)
    FuncType: id =3D {0x023ab5ce}, = byte-size =3D 0, decl =3D ip6_output.c:403, compiler_type =3D "int = (struct mbuf *, struct ip6_pktopts *, struct route_in6 *, int, struct = ip6_moptions *, struct ifnet **, struct inpcb *)"
=       Blocks: id =3D {0x023ab5ce}, range =3D= [0xffffffff80d81660-0xffffffff80d838c4)
=    LineEntry: [0xffffffff80d821b6-0xffffffff80d821c4): = /usr/src/sys/netinet6/ip6_output.c:811:3
=       Symbol: id =3D {0x000101b9}, range =3D= [0xffffffff80d81660-0xffffffff80d838c4), name=3D"ip6_output"
    Variable: id =3D {0x023ab5e8}, name = =3D "m0", type =3D "mbuf *", valid ranges =3D <block>, location =3D = [0xffffffff80d819c2, 0xffffffff80d82a26) -> = DW_OP_GNU_entry_value(DW_OP_reg5 RDI), DW_OP_stack_value, decl =3D = ip6_output.c:403
    Variable: id =3D = {0x023ab5f8}, name =3D "opt", type =3D "ip6_pktopts *", valid ranges =3D = <block>, location =3D [0xffffffff80d8168e, 0xffffffff80d838c4) = -> DW_OP_breg6 RBP-184, decl =3D ip6_output.c:403
=     Variable: id =3D {0x023ab608}, name =3D "ro", = type =3D "route_in6 *", valid ranges =3D <block>, location =3D = [0xffffffff80d81a3b, 0xffffffff80d824c0) -> DW_OP_reg3 RBX, decl =3D = ip6_output.c:404
    Variable: id =3D = {0x023ab618}, name =3D "flags", type =3D "int", valid ranges =3D = <block>, location =3D [0xffffffff80d81684, 0xffffffff80d838c4) = -> DW_OP_breg6 RBP-152, decl =3D ip6_output.c:404
=     Variable: id =3D {0x023ab628}, name =3D "im6o", = type =3D "ip6_moptions *", valid ranges =3D <block>, location =3D = [0xffffffff80d816b7, 0xffffffff80d83032) -> DW_OP_breg6 RBP-352, decl = =3D ip6_output.c:404
    Variable: id = =3D {0x023ab638}, name =3D "ifpp", type =3D "ifnet **", valid ranges =3D = <block>, location =3D [0xffffffff80d8167b, 0xffffffff80d838c4) = -> DW_OP_breg6 RBP-304, decl =3D ip6_output.c:405
=     Variable: id =3D {0x023ab648}, name =3D "inp", = type =3D "inpcb *", valid ranges =3D <block>, location =3D = DW_OP_fbreg +16, decl =3D ip6_output.c:405
=     Variable: id =3D {0x023ab657}, name =3D "m", = type =3D "mbuf *", valid ranges =3D <block>, location =3D = DW_OP_fbreg -48, decl =3D ip6_output.c:409
=     Variable: id =3D {0x023ab666}, name =3D "sin6", = type =3D "sockaddr_in6", valid ranges =3D <block>, location =3D = DW_OP_fbreg -380, decl =3D ip6_output.c:413
=     Variable: id =3D {0x023ab676}, name =3D = "src_sa", type =3D "sockaddr_in6", valid ranges =3D <block>, = location =3D DW_OP_fbreg -336, decl =3D ip6_output.c:413
=     Variable: id =3D {0x023ab686}, name =3D = "dst_sa", type =3D "sockaddr_in6", valid ranges =3D <block>, = location =3D DW_OP_fbreg -128, decl =3D ip6_output.c:413
=     Variable: id =3D {0x023ab696}, name =3D "odst", = type =3D "in6_addr", valid ranges =3D <block>, location =3D = DW_OP_fbreg -432, decl =3D ip6_output.c:414
=     Variable: id =3D {0x023ab6a6}, name =3D = "alwaysfrag", type =3D "int", valid ranges =3D <block>, location =3D= DW_OP_fbreg -192, decl =3D ip6_output.c:421
=     Variable: id =3D {0x023ab6b6}, name =3D = "exthdrs", type =3D "ip6_exthdrs", valid ranges =3D <block>, = location =3D DW_OP_fbreg -248, decl =3D ip6_output.c:423
=     Variable: id =3D {0x023ab6c6}, name =3D "src0", = type =3D "in6_addr", valid ranges =3D <block>, location =3D = DW_OP_fbreg -416, decl =3D ip6_output.c:424
=     Variable: id =3D {0x023ab6d6}, name =3D "dst0", = type =3D "in6_addr", valid ranges =3D <block>, location =3D = DW_OP_fbreg -400, decl =3D ip6_output.c:424
=     Variable: id =3D {0x023ab6e6}, name =3D "zone", = type =3D "u_int32_t", valid ranges =3D <block>, location =3D = DW_OP_fbreg -188, decl =3D ip6_output.c:425
=     Variable: id =3D {0x023ab726}, name =3D "error", = type =3D "int", valid ranges =3D <block>, location =3D = [0xffffffff80d8214f, 0xffffffff80d8251a) -> DW_OP_consts +0, = DW_OP_stack_value, decl =3D ip6_output.c:417
=     Variable: id =3D {0x023ab736}, name =3D = "vlan_pcp", type =3D "int", valid ranges =3D <block>, location =3D = [0xffffffff80d819c2, 0xffffffff80d82a18) -> DW_OP_breg6 RBP-96, decl = =3D ip6_output.c:418
    Variable: id = =3D {0x023ab746}, name =3D "ia", type =3D "in6_ifaddr *", valid ranges =3D= <block>, location =3D [0xffffffff80d82187, 0xffffffff80d82a18) = -> DW_OP_breg6 RBP-264, decl =3D ip6_output.c:419
=     Variable: id =3D {0x023ab776}, name =3D "ip6", = type =3D "ip6_hdr *", valid ranges =3D <block>, location =3D = [0xffffffff80d81e29, 0xffffffff80d82665) -> DW_OP_breg6 RBP-168, decl = =3D ip6_output.c:407
    Variable: id = =3D {0x023ab7c6}, name =3D "nexthdrp", type =3D "u_char *", valid ranges = =3D <block>, location =3D [0xffffffff80d81a4f, 0xffffffff80d82a18) = -> DW_OP_breg6 RBP-136, decl =3D ip6_output.c:415
=     Variable: id =3D {0x023ab7d6}, name =3D = "ro_pmtu", type =3D "route_in6 *", valid ranges =3D <block>, = location =3D [0xffffffff80d81ab4, 0xffffffff80d824c0) -> DW_OP_reg3 = RBX, decl =3D ip6_output.c:411
=     Variable: id =3D {0x023ab7e6}, name =3D "dst", = type =3D "sockaddr_in6 *", valid ranges =3D <block>, location =3D = [0xffffffff80d81b39, 0xffffffff80d82466) -> DW_OP_breg6 RBP-88, decl = =3D ip6_output.c:413
    Variable: id = =3D {0x023ab7f6}, name =3D "fibnum", type =3D "uint32_t", valid ranges =3D= <block>, location =3D [0xffffffff80d81b26, 0xffffffff80d827e3) = -> DW_OP_breg6 RBP-72, decl =3D ip6_output.c:429
=     Variable: id =3D {0x023ab806}, name =3D = "origifp", type =3D "ifnet *", valid ranges =3D <block>, location = =3D [0xffffffff80d8218b, 0xffffffff80d824ae) -> DW_OP_reg12 R12, decl = =3D ip6_output.c:408
    Variable: id = =3D {0x023ab876}, name =3D "tlen", type =3D "int", valid ranges =3D = <block>, location =3D <empty>, decl =3D ip6_output.c:416
    Variable: id =3D {0x023ab882}, name = =3D "dontfrag", type =3D "int", valid ranges =3D <block>, location = =3D <empty>, decl =3D ip6_output.c:421

   806 =         KASSERT((ifp !=3D NULL), = ("output interface must not be NULL"));
=    807 =         KASSERT((origifp !=3D = NULL), ("output address interface must not be NULL"));
=    808
   809 =         if ((flags & = IPV6_FORWARDING) =3D=3D 0) {
   810 =             &n= bsp;   /* XXX: the FORWARDING flag can be set for = mrouting. */
   811 =             &n= bsp;   in6_ifstat_inc(ifp, ifs6_out_request);

I'm = not quite sure, but it seems the `ifp` is not fully constructed. = See https://cgit.freebsd.org/src/tree/sys/net/if.c#n950

If I read the code correctly, the = clone created interface is made visible via `if_link_ifnet(ifp);` , and = at that time the

`ifp->if_afdata[AF_INET6]` is NULL and is = not initialized yet by `if_attachdomain1()` which will call = `in6_domifattach()`

to allocate the required = data.

So I guess there is a race = condition. I bet this can be repeated easily.

I have not tested this yet, and not sure if it is = the right fix, but you can give it a try.

diff --git a/sys/net/if.c = b/sys/net/if.c

index c3c27fbf678f..16ee5667e7bb = 100644

--- a/sys/net/if.c

+++ = b/sys/net/if.c

@@ -947,11 +947,11 @@ if_attach_internal(struct = ifnet *ifp, bool vmove)

= }

#endif

- = if_link_ifnet(ifp);

= if (domain_init_status >=3D 2)

= = if_attachdomain1(ifp);

+ = if_link_ifnet(ifp);

= EVENTHANDLER_INVOKE(ifnet_arrival_event, ifp);

= if (IS_DEFAULT_VNET(curvnet))

= devctl_notify("IFNET", = ifp->if_xname, "ATTACH", NULL);

=    812 =         }
=    813
   814 =         /* Setup data structures = for scope ID checks. */

--
Bjoern A. Zeeb =             &n= bsp;           &nbs= p;            =             &n= bsp;  r15:7

Best regards,

Zhenlei

= --Apple-Mail=_0715C355-6B28-4360-86DE-DF9D867C1F8C--