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Tsirkin" , Stefano Garzarella Subject: [PATCH] vhost-user-gpu: validate command buffer size in submit_3d Date: Mon, 13 Jul 2026 16:54:31 +0400 Message-ID: <20260713125431.107278-1-marcandre.lureau@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists1p.gnu.org; Received-SPF: permerror client-ip=170.10.133.124; envelope-from=marcandre.lureau@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 12 X-Spam_score: 1.2 X-Spam_bar: + X-Spam_report: (1.2 / 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, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, T_SPF_PERMERROR=0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1783947310925158500 From: Marc-Andr=C3=A9 Lureau virgl_cmd_submit_3d() passes the guest-controlled cs.size directly to g_malloc() without any bounds check. A malicious guest can set this field to an arbitrarily large value (up to 4GB), causing an OOM abort that crashes the vhost-user-gpu daemon. Validate cs.size against the actual descriptor payload size before allocating, rejecting values that exceed what the virtqueue entry can carry. Fixes: d52c454aadc ("contrib: add vhost-user-gpu") Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3776 Reported-by: admin@fluentlogic.org Signed-off-by: Marc-Andr=C3=A9 Lureau --- contrib/vhost-user-gpu/virgl.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/contrib/vhost-user-gpu/virgl.c b/contrib/vhost-user-gpu/virgl.c index 51da0e3667f..7b7b660653f 100644 --- a/contrib/vhost-user-gpu/virgl.c +++ b/contrib/vhost-user-gpu/virgl.c @@ -197,11 +197,21 @@ virgl_cmd_submit_3d(VuGpu *g, struct virtio_gpu_ctrl_command *cmd) { struct virtio_gpu_cmd_submit cs; + size_t iov_len; void *buf; size_t s; =20 VUGPU_FILL_CMD(cs); =20 + iov_len =3D iov_size(cmd->elem.out_sg, cmd->elem.out_num); + if (cs.size =3D=3D 0 || iov_len < sizeof(cs) || + cs.size > iov_len - sizeof(cs)) { + g_critical("%s: size out of range (%u/%zu)", + __func__, cs.size, iov_len); + cmd->error =3D VIRTIO_GPU_RESP_ERR_INVALID_PARAMETER; + return; + } + buf =3D g_malloc(cs.size); s =3D iov_to_buf(cmd->elem.out_sg, cmd->elem.out_num, sizeof(cs), buf, cs.size); --=20 2.55.0