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

[Aurelien Jarno]

On Sat, Jan 24, 2009 at 10:00:33PM +0100, Stefan Weil wrote:
> 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 fact that your host system is 64-bit and you are using the user
networking is interesting. You could try to look at revisions 6272 and
6288, they are probably the cause of your problem.

> 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.
> >   
> 
> 
> 

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
address@hidden                 http://www.aurel32.net