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[80.230.24.117]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4950a33a926sm147346705e9.15.2026.07.15.08.50.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jul 2026 08:50:43 -0700 (PDT) Date: Wed, 15 Jul 2026 11:50:40 -0400 From: "Michael S. Tsirkin" To: Hari Mishal Cc: Amit Shah , Arnd Bergmann , Greg Kroah-Hartman , Gerd Hoffmann , Jason Wang , David Hildenbrand , Henrik Rydberg , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, linux-input@vger.kernel.org Subject: Re: [PATCH 2/4] virtio_input: validate device-reported multitouch slot count Message-ID: <20260715115018-mutt-send-email-mst@kernel.org> References: <20260715142337.22811-1-harimishal1@gmail.com> <20260715142337.22811-3-harimishal1@gmail.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20260715142337.22811-3-harimishal1@gmail.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 2aEyZZ5SCoeERimOwJl-DnCh1oaNsc9QKlc6xrcrJDE_1784130645 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Wed, Jul 15, 2026 at 04:22:41PM +0200, Hari Mishal wrote: > nslots is derived from the ABS_MT_SLOT maximum reported by the > virtio device. A device could report a bogus maximum (e.g. -1) > making nslots = 0, which input_mt_init_slots() does not reject; > it returns success without allocating any slot storage, silently > leaving the device registered as multitouch capable with no > backing state. So let's disable multitouch instead? > Reject non-positive slot counts before calling > input_mt_init_slots(). > > Assisted-by: gkh_clanker:t1000 > Signed-off-by: Hari Mishal > --- > drivers/virtio/virtio_input.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/virtio/virtio_input.c b/drivers/virtio/virtio_input.c > index deec24e8e682..2cc19782cdd3 100644 > --- a/drivers/virtio/virtio_input.c > +++ b/drivers/virtio/virtio_input.c > @@ -312,6 +312,10 @@ static int virtinput_probe(struct virtio_device *vdev) > > if (test_bit(ABS_MT_SLOT, vi->idev->absbit)) { > nslots = input_abs_get_max(vi->idev, ABS_MT_SLOT) + 1; > + if (nslots <= 0) { > + err = -EINVAL; > + goto err_mt_init_slots; > + } > err = input_mt_init_slots(vi->idev, nslots, 0); > if (err) > goto err_mt_init_slots; > -- > 2.43.0