Re: [Qemu-devel] [Bug 1729501] [NEW] qemu crashes with assertion error `off_cur_end >= off_cur' failed

[Thomas Huth]

On 02.11.2017 07:14, Liang Dai wrote:
> Public bug reported:
> 
> My host environment: Xen + QEMU
> 
> git clones today's xen git and qemut git (2017-10-31)
> 
> xen  -- git://xenbits.xen.org/xen.git
> commit 24fb44e971a62b345c7b6ca3c03b454a1e150abe
>       
> qemu -- https://github.com/qemu/qemu 
> commit 47ba789c97c8d201d01058b00a14d8a9a85fcfe9
> 
> QEMU was compiled using:
> ./configure --prefix=/mnt/bin/ --enable-xen --target-list=i386-softmmu 
> --extra-cflags="-I/mnt/xen/tools/include -I/mnt/xen/tools/libxc 
> -I/mnt/xen/tools/xenstore"        --extra-ldflags="-L/mnt/xen/tools/libxc 
> -L/mnt/xen/tools/xenstore" --enable-debug --enable-debug-stack-usage
> 
> Xen was configured with the above QEMU distribution:
> ./configure --with-system-qemu=/mnt/bin/bin/qemu-system-i386
> 
> QEMU command line: 
> /mnt/bin/bin/qemu-system-i386 -xen-domid 28 -chardev 
> socket,id=libxl-cmd,path=/var/run/xen/qmp-libxl-28,server,nowait -no-shutdown 
> -mon chardev=libxl-cmd,mode=control -chardev 
> socket,id=libxenstat-cmd,path=/var/run/xen/qmp-libxenstat-28,server,nowait 
> -mon chardev=libxenstat-cmd,mode=control -nodefaults -no-user-config -name 
> ubu_hvm -vnc 0.0.0.0:1,to=99 -display none -serial pty -device 
> cirrus-vga,vgamem_mb=8 -boot order=c -smp 2,maxcpus=2 -device 
> rtl8139,id=nic0,netdev=net0,mac=00:16:3e:74:34:32 -netdev 
> type=tap,id=net0,ifname=vif28.0-emu,script=no,downscript=no -device 
> rtl8139,id=nic1,netdev=net1,mac=00:16:3e:5f:48:e4 -netdev 
> type=tap,id=net1,ifname=vif28.1-emu,script=no,downscript=no -machine xenfv -m 
> 1504 -drive 
> file=/mnt/10G.hdd,if=ide,index=0,media=disk,format=raw,cache=writeback
> 
> Produce:
> I run a fuzzer program in guest vm, it may set incorrect values for graphics 
> registers, sequencer registers and other registers.
> 
> Seeing the following error from /var/log/xen/qemu-dm-<vm-name>.log:
> qemu-system-i386: hw/display/cirrus_vga.c:712: cirrus_invalidate_region: 
> Assertion `off_cur_end >= off_cur' failed.
> 
> I can reproduce it at anytime, if you need to gather more diagnostic
> information or try test patches, I'm happy to help.
> 
> 
> gdb bt:
> #0  0x00007f81a64f8c37 in __GI_raise (address@hidden) at 
> ../nptl/sysdeps/unix/sysv/linux/raise.c:56
> #1  0x00007f81a64fc028 in __GI_abort () at abort.c:89
> #2  0x00007f81a64f1bf6 in __assert_fail_base (fmt=0x7f81a6646018 "%s%s%s:%u: 
> %s%sAssertion `%s' failed.\n%n", 
>     address@hidden "off_cur_end >= off_cur", address@hidden 
> "hw/display/cirrus_vga.c", address@hidden, 
>     address@hidden <__PRETTY_FUNCTION__.40643> "cirrus_invalidate_region") at 
> assert.c:92
> #3  0x00007f81a64f1ca2 in __GI___assert_fail (assertion=0x55d70cf8cdf2 
> "off_cur_end >= off_cur", file=0x55d70cf8cda9 "hw/display/cirrus_vga.c", 
> line=712, 
>     function=0x55d70cf8db60 <__PRETTY_FUNCTION__.40643> 
> "cirrus_invalidate_region") at assert.c:101
> #4  0x000055d70cb66445 in cirrus_invalidate_region (s=0x55d70ee3a4b0, 
> off_begin=4190568, off_pitch=1842, bytesperline=5056, lines=2922) at 
> hw/display/cirrus_vga.c:712
> #5  0x000055d70cb6660c in cirrus_bitblt_common_patterncopy (s=0x55d70ee3a4b0) 
> at hw/display/cirrus_vga.c:752
> #6  0x000055d70cb6676d in cirrus_bitblt_videotovideo_patterncopy 
> (s=0x55d70ee3a4b0) at hw/display/cirrus_vga.c:786
> #7  0x000055d70cb670c5 in cirrus_bitblt_videotovideo (s=0x55d70ee3a4b0) at 
> hw/display/cirrus_vga.c:986
> #8  0x000055d70cb678bf in cirrus_bitblt_start (s=0x55d70ee3a4b0) at 
> hw/display/cirrus_vga.c:1136
> #9  0x000055d70cb6880b in cirrus_vga_write_gr (s=0x55d70ee3a4b0, 
> reg_index=42, reg_value=228) at hw/display/cirrus_vga.c:1652
> #10 0x000055d70cb6ab86 in cirrus_vga_ioport_write (opaque=0x55d70ee3a4b0, 
> addr=975, val=228, size=1) at hw/display/cirrus_vga.c:2754
> #11 0x000055d70c91d9c0 in memory_region_write_accessor (mr=0x55d70ee4af70, 
> addr=31, value=0x7fffdaaeaf38, size=1, shift=8, mask=255, attrs=...)
>     at /mnt/qemu/memory.c:560
> #12 0x000055d70c91dc3a in access_with_adjusted_size (addr=30, 
> value=0x7fffdaaeaf38, size=2, access_size_min=1, access_size_max=1, 
>     access_fn=0x55d70c91d8c9 <memory_region_write_accessor>, 
> mr=0x55d70ee4af70, attrs=...) at /mnt/qemu/memory.c:627
> #13 0x000055d70c920f48 in memory_region_dispatch_write (mr=0x55d70ee4af70, 
> addr=30, data=58410, size=2, attrs=...) at /mnt/qemu/memory.c:1503
> #14 0x000055d70c8c51e0 in flatview_write_continue (fv=0x55d70ecb66d0, 
> addr=974, attrs=..., buf=0x7fffdaaeb0f0 "*\344W\026\377\177", len=4, 
> addr1=30, l=2, 
>     mr=0x55d70ee4af70) at /mnt/qemu/exec.c:2951
> #15 0x000055d70c8c5390 in flatview_write (fv=0x55d70ecb66d0, addr=974, 
> attrs=..., buf=0x7fffdaaeb0f0 "*\344W\026\377\177", len=4) at 
> /mnt/qemu/exec.c:3002
> #16 0x000055d70c8c5406 in address_space_write (as=0x55d70d70d5e0 
> <address_space_io>, addr=974, attrs=..., buf=0x7fffdaaeb0f0 
> "*\344W\026\377\177", len=4)
>     at /mnt/qemu/exec.c:3014
> #17 0x000055d70c914fb3 in cpu_outl (addr=974, val=374858794) at 
> /mnt/qemu/ioport.c:81
> #18 0x000055d70ca0253f in do_outp (addr=974, size=4, val=374858794) at 
> /mnt/qemu/hw/i386/xen/xen-hvm.c:782
> #19 0x000055d70ca02888 in cpu_ioreq_pio (req=0x7fffdaaeb210) at 
> /mnt/qemu/hw/i386/xen/xen-hvm.c:852
> #20 0x000055d70ca02f2e in handle_ioreq (state=0x55d70e0cf3d0, 
> req=0x7fffdaaeb210) at /mnt/qemu/hw/i386/xen/xen-hvm.c:961
> #21 0x000055d70ca0343e in cpu_handle_ioreq (opaque=0x55d70e0cf3d0) at 
> /mnt/qemu/hw/i386/xen/xen-hvm.c:1089
> #22 0x000055d70ce75d69 in aio_dispatch_handlers (ctx=0x55d70e098550) at 
> util/aio-posix.c:406
> #23 0x000055d70ce75f0b in aio_dispatch (ctx=0x55d70e098550) at 
> util/aio-posix.c:437
> #24 0x000055d70ce70b46 in aio_ctx_dispatch (source=0x55d70e098550, 
> callback=0x0, user_data=0x0) at util/async.c:261
> #25 0x00007f81a7215e04 in g_main_context_dispatch () from 
> /lib/x86_64-linux-gnu/libglib-2.0.so.0
> #26 0x000055d70ce74455 in glib_pollfds_poll () at util/main-loop.c:214
> #27 0x000055d70ce7456a in os_host_main_loop_wait (timeout=16061710) at 
> util/main-loop.c:261
> #28 0x000055d70ce7463f in main_loop_wait (nonblocking=0) at 
> util/main-loop.c:515
> #29 0x000055d70ca8e6a6 in main_loop () at vl.c:1995
> #30 0x000055d70ca96815 in main (argc=42, argv=0x7fffdaaeb888, 
> envp=0x7fffdaaeb9e0) at vl.c:4897

Can you also reproduce this without Xen? And is the fuzzer available
publicly somewhere?