[Bug 233955] [panic] Page fault in in6_purgeaddr (triggered by net/wireguard)

Sat Apr 20 14:09:56 UTC 2019

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=233955

--- Comment #16 from genneko217 at gmail.com ---
(In reply to Jason A. Donenfeld from comment #15)
As I've been recently playing with WireGuard on FreeBSD again,
I quickly tested the patch on a 4-core FreeBSD 12.0p3 VM and found
it almost worked around the kernel issue.

With the patched wireguard-go, only 2 out of 25000+ "service wireguard
restart" caused kernel panic, while panic occured every 5 to 50 restarts
without the patch.

As a side note, I also noticed in my recent testing

- No kernel panic on single-core FreeBSD 12.0p3 / 13-CURRENT VMs
  with the unpatched wireguard-go-0.0.20181222 / 20190409
  and 10000+ restarts.

- No kernel panic on a 4-core FreeBSD 13-CURRENT r346132 VM with
  the unpatched wireguard-go-0.0.20190409 and 40000+ restarts.

A stacktrace of the panic with the patch is as follows.
(Panics without the patch are the same as the one mentioned in
 comment #4 and #11.)

Hope this helps.

 dumped core - see /var/crash/vmcore.2

Sat Apr 20 12:07:44 UTC 2019

FreeBSD  12.0-RELEASE-p3 FreeBSD 12.0-RELEASE-p3 GENERIC  amd64

panic: page fault

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Unread portion of the kernel message buffer:
panic: page fault
cpuid = 1
time = 1555762025
KDB: stack backtrace:
#0 0xffffffff80be7977 at kdb_backtrace+0x67
#1 0xffffffff80b9b563 at vpanic+0x1a3
#2 0xffffffff80b9b3b3 at panic+0x43
#3 0xffffffff8107496f at trap_fatal+0x35f
#4 0xffffffff810749c9 at trap_pfault+0x49
#5 0xffffffff81073fee at trap+0x29e
#6 0xffffffff8104f435 at calltrap+0x8
#7 0xffffffff80ca90d7 at tunifioctl+0x257
#8 0xffffffff80c9a072 at ifhwioctl+0x2f2
#9 0xffffffff80c9c05f at ifioctl+0x45f
#10 0xffffffff80c04f3d at kern_ioctl+0x26d
#11 0xffffffff80c04c5e at sys_ioctl+0x15e
#12 0xffffffff81075449 at amd64_syscall+0x369
#13 0xffffffff8104fd1d at fast_syscall_common+0x101
Uptime: 22m44s
Dumping 171 out of 469 MB:..10%..19%..29%..38%..47%..57%..66%..75%..85%..94%

Reading symbols from /boot/kernel/zfs.ko...Reading symbols from
/usr/lib/debug//boot/kernel/zfs.ko.debug...done.
done.
Loaded symbols for /boot/kernel/zfs.ko
Reading symbols from /boot/kernel/opensolaris.ko...Reading symbols from
/usr/lib/debug//boot/kernel/opensolaris.ko.debug...done.
done.
Loaded symbols for /boot/kernel/opensolaris.ko
Reading symbols from /boot/modules/vboxguest.ko...done.
Loaded symbols for /boot/modules/vboxguest.ko
Reading symbols from /boot/kernel/intpm.ko...Reading symbols from
/usr/lib/debug//boot/kernel/intpm.ko.debug...done.
done.
Loaded symbols for /boot/kernel/intpm.ko
Reading symbols from /boot/kernel/smbus.ko...Reading symbols from
/usr/lib/debug//boot/kernel/smbus.ko.debug...done.
done.
Loaded symbols for /boot/kernel/smbus.ko
#0  doadump (textdump=<value optimized out>) at pcpu.h:230
230     pcpu.h: No such file or directory.
        in pcpu.h
(kgdb) #0  doadump (textdump=<value optimized out>) at pcpu.h:230
#1  0xffffffff80b9b14b in kern_reboot (howto=260)
    at /usr/src/sys/kern/kern_shutdown.c:446
#2  0xffffffff80b9b5c3 in vpanic (fmt=<value optimized out>,
    ap=<value optimized out>) at /usr/src/sys/kern/kern_shutdown.c:872
#3  0xffffffff80b9b3b3 in panic (fmt=<value optimized out>)
    at /usr/src/sys/kern/kern_shutdown.c:799
#4  0xffffffff8107496f in trap_fatal (frame=0xfffffe000fe94590, eva=1040)
    at /usr/src/sys/amd64/amd64/trap.c:929
#5  0xffffffff810749c9 in trap_pfault (frame=0xfffffe000fe94590, usermode=0)
    at pcpu.h:230
#6  0xffffffff81073fee in trap (frame=0xfffffe000fe94590)
    at /usr/src/sys/amd64/amd64/trap.c:441
#7  0xffffffff8104f435 in calltrap ()
    at /usr/src/sys/amd64/amd64/exception.S:232
#8  0xffffffff80b7ad4c in __mtx_lock_sleep (c=0xfffff8001045bc98, v=4)
    at /usr/src/sys/kern/kern_mutex.c:577
#9  0xffffffff80ca90d7 in tunifioctl (ifp=<value optimized out>,
    cmd=<value optimized out>, data=0xfffff80002f98c00 "wg0")
    at /usr/src/sys/net/if_tun.c:543
#10 0xffffffff80c9a072 in ifhwioctl (cmd=<value optimized out>,
    ifp=<value optimized out>, data=<value optimized out>,
    td=0xfffff80002f22000) at /usr/src/sys/net/if.c:2881
#11 0xffffffff80c9c05f in ifioctl (so=0xfffff8000969b6d0, cmd=3274795323,
    data=<value optimized out>, td=0xfffff80002f22000)
    at /usr/src/sys/net/if.c:3086
#12 0xffffffff80c04f3d in kern_ioctl (td=0xfffff80002f22000, fd=3,
    com=3274795323, data=<value optimized out>) at file.h:330
#13 0xffffffff80c04c5e in sys_ioctl (td=0xfffff80002f22000,
    uap=0xfffff80002f223c0) at /usr/src/sys/kern/sys_generic.c:712
#14 0xffffffff81075449 in amd64_syscall (td=0xfffff80002f22000, traced=0)
    at subr_syscall.c:135
#15 0xffffffff8104fd1d in fast_syscall_common ()
    at /usr/src/sys/amd64/amd64/exception.S:504
#16 0x000000080046611a in ?? ()
Previous frame inner to this frame (corrupt stack?)
Current language:  auto; currently minimal
(kgdb)

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