Re: [PATCH-for-6.2 v3 2/2] tests/qtest/fdc-test: Add a regression test for CVE-2021-20196

[Philippe Mathieu-Daudé]

On 11/23/21 15:14, Hanna Reitz wrote:
> On 23.11.21 14:49, Philippe Mathieu-Daudé wrote:
>> On 11/23/21 14:42, Hanna Reitz wrote:
>>> On 18.11.21 13:06, Philippe Mathieu-Daudé wrote:
>>>> From: Alexander Bulekov <alxndr@bu.edu>
>>>>
>>>> Without the previous commit, when running 'make check-qtest-i386'
>>>> with QEMU configured with '--enable-sanitizers' we get:
>>>>
>>>>     AddressSanitizer:DEADLYSIGNAL
>>>>     =================================================================
>>>>     ==287878==ERROR: AddressSanitizer: SEGV on unknown address
>>>> 0x000000000344
>>>>     ==287878==The signal is caused by a WRITE memory access.
>>>>     ==287878==Hint: address points to the zero page.
>>>>         #0 0x564b2e5bac27 in blk_inc_in_flight
>>>> block/block-backend.c:1346:5
>>>>         #1 0x564b2e5bb228 in blk_pwritev_part
>>>> block/block-backend.c:1317:5
>>>>         #2 0x564b2e5bcd57 in blk_pwrite block/block-backend.c:1498:11
>>>>         #3 0x564b2ca1cdd3 in fdctrl_write_data hw/block/fdc.c:2221:17
>>>>         #4 0x564b2ca1b2f7 in fdctrl_write hw/block/fdc.c:829:9
>>>>         #5 0x564b2dc49503 in portio_write softmmu/ioport.c:201:9
>>>>
>>>> Add the reproducer for CVE-2021-20196.
>>>>
>>>> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
>>>> Message-Id: <20210319050906.14875-2-alxndr@bu.edu>
>>>> [PMD: Rebased, use global test_image]
>>>> Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
>>>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>>>> ---
>>>>    tests/qtest/fdc-test.c | 21 +++++++++++++++++++++
>>>>    1 file changed, 21 insertions(+)
>>> Not sure if I’m doing something wrong, but:
>>>
>>> Using the global test_image brings a problem, namely that this test
>>> fails unconditionally (for me at least...?), with the reason being that
>>> the global QEMU instance (launched by qtest_start(), quit by
>>> qtest_end()) still has that image open, so by launching a second
>>> instance concurrently, I get this:
>>>
>>> qemu-system-x86_64: Failed to get "write" lock
>>> Is another process using the image [/tmp/qtest.xV4IxX]?
>> Hmm I had too many odd problems running qtests in parallel so I
>> switched to 'make check-qtest -j1' more than 1 year ago, which
>> is probably why I haven't noticed that issue.
> 
> I’ve run the test with
> 
> QTEST_QEMU_BINARY=$PWD/qemu-system-x86_64 tests/qtest/fdc-test
> 
> so there definitely weren’t any other tests running at the same time.  I
> don’t know why you don’t encounter this problem, but it’s caused by the
> concurrent QEMU instance launched in the very same test (qtest_start()
> in main(), and cleaned up by qtest_end() after g_test_run()).

I run all my qtests on top of this patch, otherwise I can't
get any coredump:
https://lore.kernel.org/qemu-devel/20200707031920.17428-1-f4bug@amsat.org/
But I don't think it mattered here...