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[81.40.121.39]) by smtp.gmail.com with ESMTPSA id q126sm5078248wma.6.2021.04.17.22.14.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 17 Apr 2021 22:14:37 -0700 (PDT) Subject: Re: [PATCH-for-6.0?] mptsas: remove unused MPTSASState.pending (CVE-2021-3392) From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= To: Michael Tokarev , qemu-devel@nongnu.org, Fam Zheng , Paolo Bonzini References: <20210416102243.1293871-1-mjt@msgid.tls.msk.ru> <8c313f51-db0d-c9c0-621d-a9af689b7164@redhat.com> Message-ID: Date: Sun, 18 Apr 2021 07:14:36 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=philmd@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=philmd@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, 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=unavailable 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 , Prasad J Pandit , qemu-trivial@nongnu.org, Don Slutz , Li Qiang , qemu-stable@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 4/16/21 1:33 PM, Philippe Mathieu-Daudé wrote: > Cc'ing maintainers. > > On 4/16/21 1:27 PM, Philippe Mathieu-Daudé wrote: >> On 4/16/21 12:22 PM, Michael Tokarev wrote: >>> During previous attempt to fix CVE-2021-3392 it was discovered >>> that MPTSASState.pending is actually not used. So instead of >>> fixing the prob, just remove the offending code entirely >> >> What problem? Digging a bit I found: https://bugs.launchpad.net/qemu/+bug/1914236 and Paolo's comment: https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg02660.html So your patch now makes sense, but please: 1/ Reword including Prasad description: """ While processing SCSI i/o requests in mptsas_process_scsi_io_request(), the Megaraid emulator appends new MPTSASRequest object 'req' to the 's->pending' queue. In case of an error, this same object gets dequeued in mptsas_free_request() only if SCSIRequest object 'req->sreq' is initialised. This may lead to a use-after-free issue. Since MPTSASState.pending is actually not used, simply remove it. """ 2/ Add: BugLink: https://bugs.launchpad.net/qemu/+bug/1914236 (CVE-2021-3392) Fixes: e351b826112 ("hw: Add support for LSI SAS1068 (mptsas) device") With it: Reviewed-by: Philippe Mathieu-Daudé >>> Signed-off-by: Michael Tokarev >>> Cc: Prasad J Pandit >>> Cc: qemu-stable@nongnu.org >>> --- >>> hw/scsi/mptsas.c | 4 ---- >>> hw/scsi/mptsas.h | 1 - >>> 2 files changed, 5 deletions(-) >>> >>> diff --git a/hw/scsi/mptsas.c b/hw/scsi/mptsas.c >>> index 7416e78706..5abbc742aa 100644 >>> --- a/hw/scsi/mptsas.c >>> +++ b/hw/scsi/mptsas.c >>> @@ -257,7 +257,6 @@ static void mptsas_free_request(MPTSASRequest *req) >>> req->sreq->hba_private = NULL; >>> scsi_req_unref(req->sreq); >>> req->sreq = NULL; >>> - QTAILQ_REMOVE(&s->pending, req, next); >>> } >>> qemu_sglist_destroy(&req->qsg); >>> g_free(req); >>> @@ -303,7 +302,6 @@ static int mptsas_process_scsi_io_request(MPTSASState *s, >>> } >>> >>> req = g_new0(MPTSASRequest, 1); >>> - QTAILQ_INSERT_TAIL(&s->pending, req, next); >>> req->scsi_io = *scsi_io; >>> req->dev = s; >>> >>> @@ -1319,8 +1317,6 @@ static void mptsas_scsi_realize(PCIDevice *dev, Error **errp) >>> >>> s->request_bh = qemu_bh_new(mptsas_fetch_requests, s); >>> >>> - QTAILQ_INIT(&s->pending); >>> - >>> scsi_bus_new(&s->bus, sizeof(s->bus), &dev->qdev, &mptsas_scsi_info, NULL); >>> } >>> >>> diff --git a/hw/scsi/mptsas.h b/hw/scsi/mptsas.h >>> index b85ac1a5fc..c046497db7 100644 >>> --- a/hw/scsi/mptsas.h >>> +++ b/hw/scsi/mptsas.h >>> @@ -79,7 +79,6 @@ struct MPTSASState { >>> uint16_t reply_frame_size; >>> >>> SCSIBus bus; >>> - QTAILQ_HEAD(, MPTSASRequest) pending; >>> }; >>> >>> void mptsas_fix_scsi_io_endianness(MPIMsgSCSIIORequest *req); >>> >> >