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Mon, 23 Aug 2021 02:59:18 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzsyd+9TZ1+PriaZnqHT9WSyOIZOgsmsj8EnI8QdmAx8qofmfn2WtinQiLJ169TyzhYesfk5NoeRZDEztoBUNw= X-Received: by 2002:a17:902:ecca:b029:12d:1a3b:571f with SMTP id a10-20020a170902eccab029012d1a3b571fmr27572823plh.37.1629712758043; Mon, 23 Aug 2021 02:59:18 -0700 (PDT) MIME-Version: 1.0 References: <20210818120505.1258262-1-kraxel@redhat.com> In-Reply-To: From: Mauro Matteo Cascella Date: Mon, 23 Aug 2021 11:59:07 +0200 Message-ID: Subject: Re: [PATCH 0/1] uas: add stream number sanity checks (maybe 6.1) To: =?UTF-8?Q?Philippe_Mathieu=2DDaud=C3=A9?= Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mcascell@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=170.10.133.124; envelope-from=mcascell@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.746, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Gerd Hoffmann , QEMU Developers Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi, On Fri, Aug 20, 2021 at 3:07 PM Philippe Mathieu-Daud=C3=A9 wrote: > > Cc'ing Mauro to double-check. > > On 8/20/21 2:12 PM, Peter Maydell wrote: > > On Wed, 18 Aug 2021 at 13:10, Gerd Hoffmann wrote: > >> > >> Security fix. Sorry for the last-minute patch, I had completely > >> forgotten this one until the CVE number for it arrived today. > >> > >> Given that the classic usb storage device is way more popular than > >> the uas (usb attached scsi) device the impact should be pretty low > >> and we might consider to not screw up our release schedule for this. > > > > What's the impact if the bug is exploited ? > > Bug class: "guest-triggered user-after-free". > > Being privileged (root) in the guest, you can leak some data from > the host process then DoS the host or potentially exploit the > use-after-free to execute code on the host. > This is actually an out-of-bounds access issue (not UAF). It's still potentially bad, but I agree with Gerd the impact is low. Plus there's an assert right before [1] that makes it a DoS if the accessed memory is not NULL. [1] https://gitlab.com/qemu-project/qemu/-/blob/master/hw/usb/dev-uas.c#L85= 0 Regards. -- Mauro Matteo Cascella Red Hat Product Security PGP-Key ID: BB3410B0