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

[Stefan Weil <weil@mail.berlios.de>]

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.

Regards
Stefan Weil

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