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([2a02:8071:5055:3f20:7ad9:a400:6d51:83e6]) by smtp.gmail.com with ESMTPSA id h16sm13035662wrm.27.2021.11.23.06.14.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 23 Nov 2021 06:14:54 -0800 (PST) Message-ID: Date: Tue, 23 Nov 2021 15:14:53 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Subject: Re: [PATCH-for-6.2 v3 2/2] tests/qtest/fdc-test: Add a regression test for CVE-2021-20196 To: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , qemu-devel@nongnu.org References: <20211118120635.4043197-1-philmd@redhat.com> <20211118120635.4043197-3-philmd@redhat.com> <1cca5391-18e9-8e29-9c8b-0d44010cdecd@redhat.com> From: Hanna Reitz In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=hreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -69 X-Spam_score: -7.0 X-Spam_bar: ------- X-Spam_report: (-7.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.7, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-3.515, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Laurent Vivier , Kevin Wolf , Thomas Huth , Prasad J Pandit , qemu-block@nongnu.org, Darren Kenny , Markus Armbruster , Alexander Bulekov , =?UTF-8?Q?Herv=c3=a9_Poussineau?= , Paolo Bonzini , Gaoning Pan , John Snow Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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 >>> >>> 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 >>> Message-Id: <20210319050906.14875-2-alxndr@bu.edu> >>> [PMD: Rebased, use global test_image] >>> Reviewed-by: Darren Kenny >>> Signed-off-by: Philippe Mathieu-Daudé >>> --- >>>   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()). > Using another 'test_image' seems against code reuse principle, > but at this point in release, duplicating it is simpler. Someone > will clean that later =) > >> So either we need to use a different image file, or we need to quit the >> global instance before using it (e.g. putting a qtest_end() at the >> beginning of test_cve_*()), although the latter just seems wrong. >> >> Second, I can’t make this test fail.  When I apply this patch first (to >> master) and run it, I don’t get a SIGSEGV. > Is your QEMU built with --enable-sanitizers ? Uh, no.  I had (wrongly) assumed there’d be no need, given that the SIGSEGV access address is below 4 kB... I now did configure and compile it with --enable-sanitizers but still can’t reproduce it. Hanna