Re: [Qemu-devel] slirp-related crash

[Jan Kiszka]

On 2012-02-12 19:34, Michael S. Tsirkin wrote:
> It seems somewhat easy to crash qemu with slirp if we queue multiple packets.
> I didn't investigate further yet so I don't know if this
> is a regression. Anyone knowledgeable about slirp wants to take a look?
> 
> /home/mst/qemu-test/bin/qemu-system-x86_64  -enable-kvm -m 1G -drive
> file=/home/mst/rhel6.qcow2 -netdev user,id=bar -net
> nic,netdev=bar,model=e1000,macaddr=52:54:00:12:34:57  -redir
> tcp:8022::22  -vnc :1 -monitor stdio
> 
> While guest is booting, quickly do this
> 
> ssh localhost -p 8022
> CTRL-C
> ssh localhost -p 8022
> CTRL-C
> ssh localhost -p 8022
> CTRL-C
> ssh localhost -p 8022
> CTRL-C

Confirmed. A single canceled connection prior the interface setup is
enough. Possibly something is not properly removed / cleaned up here.
Will see if I find some time to debug, can't promise.

Jan

> 
> When guest triest to bring up link,
> qemu crashes:
> 
> Program received signal SIGSEGV, Segmentation fault.
> 0x00007ffff7e4f8a7 in slirp_insque (a=0x0, b=0x7ffff91681f0) at
> slirp/misc.c:27
> 27              element->qh_link = head->qh_link;
> (gdb) where
> #0  0x00007ffff7e4f8a7 in slirp_insque (a=0x0, b=0x7ffff91681f0) at
> slirp/misc.c:27
> #1  0x00007ffff7e4ddd8 in if_start (slirp=0x7ffff8b0e4f0) at
> slirp/if.c:194
> #2  0x00007ffff7e51290 in slirp_select_poll (readfds=0x7fffffffdfe0,
> writefds=
>     0x7fffffffdf60, xfds=0x7fffffffdee0, select_error=0) at
> slirp/slirp.c:588
> #3  0x00007ffff7e114c3 in main_loop_wait (nonblocking=<value optimized
> out>)
>     at main-loop.c:466
> #4  0x00007ffff7e09ed4 in main_loop (argc=<value optimized out>, 
>     argv=<value optimized out>, envp=<value optimized out>)
>     at /home/mst/scm/qemu/vl.c:1482
> #5  main (argc=<value optimized out>, argv=<value optimized out>, 
>     envp=<value optimized out>) at /home/mst/scm/qemu/vl.c:3525
> (gdb) p element
> $1 = (struct quehead *) 0x0
> 
>

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