Re: [Qemu-devel] [BUG] Regression in networking code (SIGSEGV)

[Stefan Weil]

Gleb Natapov schrieb:
> On Wed, Jan 21, 2009 at 10:17:20PM +0100, Stefan Weil wrote:
>   
>> Hi,
>>
>> the SIGSEGV crash below can be reproduced with Qemu r6391 and "high" net
>> load.
>>
>> I bootet a mips malta kernel from a debian nfs root. While this worked fine,
>> aptitude update hangs during downloads, nfs root is lost and after some time
>> Qemu gets a SIGSEGV.
>>
>> A similar crash occurs with a different mips machine (ar7) and different
>> network hardware (ar7 emac / cpmac), so it is not restricted to pcnet.
>> This second system does not survive the network boot.
>>
>> Up to now, I could not run tests with non-mips systems.
>>
>> I'm fairly sure that 2 weeks ago networking worked without problems in both
>> cases.
>>
>>     
> What is your host CPU?  How you run qemu (what is your command line)?
>   

Debian amd64 host.

mipsel-softmmu/qemu-system-mipsel --kernel vmlinux \
    --append "debug nohz=off root=/dev/nfs rw ip=::::malta-le::dhcp" \
    -M malta --net nic --net user -m 256

The target system is Debian mips.

Regards
Stefan

>> Program received signal SIGSEGV, Segmentation fault.
>> [Switching to Thread 0x7f3be89386e0 (LWP 14845)]
>> 0x00000000004d1a6f in ip_reass (ip=0xfe96e0, fp=0x1109050) at
>> ~/src/qemu/trunk/slirp/ip_input.c:408
>> 408             ip->ip_len = next;
>> (gdb) i s
>> #0  0x00000000004d1a6f in ip_reass (ip=0xfe96e0, fp=0x1109050) at
>> ~/src/qemu/trunk/slirp/ip_input.c:408
>> #1  0x00000000004d15ad in ip_input (m=0x110e010) at
>> ~/src/qemu/trunk/slirp/ip_input.c:228
>> #2  0x00000000004b3d25 in slirp_input (pkt=0x12fcbd0 "RT", pkt_len=1294)
>> at ~/src/qemu/trunk/slirp/slirp.c:679
>> #3  0x000000000049a07d in qemu_send_packet (vc1=0x10ff440, buf=0x12fcbd0
>> "RT", size=1294) at ~/src/qemu/trunk/net.c:399
>> #4  0x000000000042ea6a in pcnet_transmit (s=0x12fc810) at
>> ~/src/qemu/trunk/hw/pcnet.c:1300
>> #5  0x000000000042ebd8 in pcnet_poll_timer (opaque=<value optimized
>> out>) at ~/src/qemu/trunk/hw/pcnet.c:1363
>> #6  0x000000000042f270 in pcnet_ioport_writew (opaque=0x7f3be72a79e0,
>> addr=17884784, val=16684768)
>>     at ~/src/qemu/trunk/hw/pcnet.c:1645
>> #7  0x0000000000405eb8 in ioport_write (index=1, address=4146, data=0)
>> at ~/src/qemu/trunk/vl.c:302
>> #8  0x00000000004062b5 in cpu_outw (env=0x0, addr=4146, val=0) at
>> ~/src/qemu/trunk/vl.c:432
>> #9  0x00000000420ae755 in ?? ()
>> #10 0x0000000000000000 in ?? ()
>> (gdb) up
>> #1  0x00000000004d15ad in ip_input (m=0x110e010) at
>> ~/src/qemu/trunk/slirp/ip_input.c:228
>> 228                             ip = ip_reass(ip, fp);
>> (gdb) p ip
>> $1 = (struct ip *) 0x110e060
>> (gdb) do
>> #0  0x00000000004d1a6f in ip_reass (ip=0xfe96e0, fp=0x1109050) at
>> ~/src/qemu/trunk/slirp/ip_input.c:408
>> 408             ip->ip_len = next;
>> (gdb) p *ip
>> Cannot access memory at address 0xfe96e0
>>
>>
>>
>>     
>
> --
>                       Gleb.
>