10.0-RC1: net/mpd5 crashes in NgMkSockNode due to stack alignment on ARM EABI

[Adrian Chadd]

Hi!

Would you mind filing a PR with what you've put in the email? That way
it is less likely to get lost.

Thanks!



-a


On 21 December 2013 09:24, Guy Yur <guyyur at gmail.com> wrote:
> Hi,
>
> I am running 10.0-RC1 on the BeagleBone Black and the net/mpd5 port is
> crashing in libnetgraph NgMkSockNode due to stack alignment.
>
> 10.0-RC1 World and kernel were compiled in a VirtualBox VM running
> 9.2-RELEASE-p2 i386.
> clang and ARM_EABI used as the default make options.
>
> Added prints in NgMkSockNode show rbuf is aligned on 2-byte and not
> 4-byte which is needed to access ni->id (a uint32_t).
>
> ni = 0xbfffe87a
> rbuf = 0xbfffe842
> sizeof(resp->header) = 56
>
>
> (gdb) bt
> #0  0x201529a0 in NgMkSockNode (name=<value optimized out>, csp=0xbfffe95c,
>     dsp=0xbfffe958) at /usr/src/lib/libnetgraph/sock.c:134
> #1  0x00037b9c in MppcTestCap () at ccp_mppc.c:754
> #2  0x0007c1f4 in main (ac=4, av=0xbfffeb90) at main.c:248
> #3  0x0000d1b0 in __start (argc=4, argv=0xbfffeb90, env=0xbfffeba4,
>     ps_strings=<value optimized out>, obj=<value optimized out>,
>     cleanup=<value optimized out>) at /usr/src/lib/csu/arm/crt1.c:115
> #4  0x203e9dc0 in _thr_ast (curthread=0x200fd000)
>     at /usr/src/lib/libthr/thread/thr_sig.c:265
>
>
> Putting rbuf in a union with struct ng_mesg sorted the alignment to
> 4-byte and mpd5 didn't crash.
> I attached the changes I used to test mpd5 doesn't crash with correct alignment.
>
>
> Regards,
> Guy
>
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