Re: [PATCH-for-6.2 2/2] tests/qtest/fdc-test: Add a regression test for CVE-2021-3507

[Hanna Reitz <hreitz@redhat.com>]

On 18.11.21 12:57, Philippe Mathieu-Daudé wrote:
> Add the reproducer from https://gitlab.com/qemu-project/qemu/-/issues/339
>
> Without the previous commit, when running 'make check-qtest-i386'
> with QEMU configured with '--enable-sanitizers' we get:
>
>    ==4028352==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x619000062a00 at pc 0x5626d03c491a bp 0x7ffdb4199410 sp 0x7ffdb4198bc0
>    READ of size 786432 at 0x619000062a00 thread T0
>        #0 0x5626d03c4919 in __asan_memcpy (qemu-system-i386+0x1e65919)
>        #1 0x5626d1c023cc in flatview_write_continue softmmu/physmem.c:2787:13
>        #2 0x5626d1bf0c0f in flatview_write softmmu/physmem.c:2822:14
>        #3 0x5626d1bf0798 in address_space_write softmmu/physmem.c:2914:18
>        #4 0x5626d1bf0f37 in address_space_rw softmmu/physmem.c:2924:16
>        #5 0x5626d1bf14c8 in cpu_physical_memory_rw softmmu/physmem.c:2933:5
>        #6 0x5626d0bd5649 in cpu_physical_memory_write include/exec/cpu-common.h:82:5
>        #7 0x5626d0bd0a07 in i8257_dma_write_memory hw/dma/i8257.c:452:9
>        #8 0x5626d09f825d in fdctrl_transfer_handler hw/block/fdc.c:1616:13
>        #9 0x5626d0a048b4 in fdctrl_start_transfer hw/block/fdc.c:1539:13
>        #10 0x5626d09f4c3e in fdctrl_write_data hw/block/fdc.c:2266:13
>        #11 0x5626d09f22f7 in fdctrl_write hw/block/fdc.c:829:9
>        #12 0x5626d1c20bc5 in portio_write softmmu/ioport.c:207:17
>
>    0x619000062a00 is located 0 bytes to the right of 512-byte region [0x619000062800,0x619000062a00)
>    allocated by thread T0 here:
>        #0 0x5626d03c66ec in posix_memalign (qemu-system-i386+0x1e676ec)
>        #1 0x5626d2b988d4 in qemu_try_memalign util/oslib-posix.c:210:11
>        #2 0x5626d2b98b0c in qemu_memalign util/oslib-posix.c:226:27
>        #3 0x5626d09fbaf0 in fdctrl_realize_common hw/block/fdc.c:2341:20
>        #4 0x5626d0a150ed in isabus_fdc_realize hw/block/fdc-isa.c:113:5
>        #5 0x5626d2367935 in device_set_realized hw/core/qdev.c:531:13
>
>    SUMMARY: AddressSanitizer: heap-buffer-overflow (qemu-system-i386+0x1e65919) in __asan_memcpy
>    Shadow bytes around the buggy address:
>      0x0c32800044f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
>      0x0c3280004500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>      0x0c3280004510: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>      0x0c3280004520: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>      0x0c3280004530: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>    =>0x0c3280004540:[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
>      0x0c3280004550: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
>      0x0c3280004560: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
>      0x0c3280004570: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
>      0x0c3280004580: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
>      0x0c3280004590: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
>    Shadow byte legend (one shadow byte represents 8 application bytes):
>      Addressable:           00
>      Heap left redzone:       fa
>      Freed heap region:       fd
>    ==4028352==ABORTING
>
> Reported-by: Alexander Bulekov <alxndr@bu.edu>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>   tests/qtest/fdc-test.c | 20 ++++++++++++++++++++
>   1 file changed, 20 insertions(+)
>
> diff --git a/tests/qtest/fdc-test.c b/tests/qtest/fdc-test.c
> index 26b69f7c5cd..f164d972d10 100644
> --- a/tests/qtest/fdc-test.c
> +++ b/tests/qtest/fdc-test.c
> @@ -546,6 +546,25 @@ static void fuzz_registers(void)
>       }
>   }
>   
> +static void test_cve_2021_3507(void)
> +{
> +    QTestState *s;
> +
> +    s = qtest_initf("-nographic -m 32M -nodefaults "
> +                    "-drive file=%s,format=raw,if=floppy", test_image);
> +    qtest_outl(s, 0x9, 0x0a0206);
> +    qtest_outw(s, 0x3f4, 0x1600);
> +    qtest_outw(s, 0x3f4, 0x0000);
> +    qtest_outw(s, 0x3f4, 0x0000);
> +    qtest_outw(s, 0x3f4, 0x0000);
> +    qtest_outw(s, 0x3f4, 0x0200);
> +    qtest_outw(s, 0x3f4, 0x0200);
> +    qtest_outw(s, 0x3f4, 0x0000);
> +    qtest_outw(s, 0x3f4, 0x0000);
> +    qtest_outw(s, 0x3f4, 0x0000);

No idea what this does (looks like a 256-byte sector read read from 
sector 2 with EOT=0), but hits the problem and reproduces for me.

Unfortunately, I have the exact same problem with test_image as I did in 
the other series.

Hanna

> +    qtest_quit(s);
> +}
> +
>   int main(int argc, char **argv)
>   {
>       int fd;
> @@ -576,6 +595,7 @@ int main(int argc, char **argv)
>       qtest_add_func("/fdc/read_no_dma_18", test_read_no_dma_18);
>       qtest_add_func("/fdc/read_no_dma_19", test_read_no_dma_19);
>       qtest_add_func("/fdc/fuzz-registers", fuzz_registers);
> +    qtest_add_func("/fdc/fuzz/cve_2021_3507", test_cve_2021_3507);
>   
>       ret = g_test_run();
>