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Tsirkin" To: qemu-devel@nongnu.org Cc: Stefano Garzarella Subject: [PATCH] libvhost-user: protect against OOB vring queue access Message-ID: MIME-Version: 1.0 Content-Disposition: inline X-Mailer: git-send-email 2.51.2.2891.g4157995a80.dirty X-Mutt-Fcc: =sent 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: pass client-ip=170.10.133.124; envelope-from=mst@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=-1.419, 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=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-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: 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-Zoho-Virus-Status: 1 X-Zoho-AV-Stamp: zmail-av-0.2.10.1.5.2/284.895.97 X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1784899117754158501 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" SET_VRING_NUM, SET_VRING_ADDR, SET_VRING_BASE, and GET_VRING_BASE handlers all use the queue index from the message to access dev->vq[] without checking that it is below dev->max_queues, so a malformed message causes an out-of-bounds heap access. Frontend is trusted so not a security problem, but an OOB access is not a nice way to handle errors. Check, and panic. Fixes: 7b2e5c65f4 ("contrib: add libvhost-user") Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3741 Cc: Stefano Garzarella Signed-off-by: Michael S. Tsirkin --- subprojects/libvhost-user/libvhost-user.c | 28 ++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) diff --git a/subprojects/libvhost-user/libvhost-user.c b/subprojects/libvho= st-user/libvhost-user.c index 8208265588..42a5e2f1f5 100644 --- a/subprojects/libvhost-user/libvhost-user.c +++ b/subprojects/libvhost-user/libvhost-user.c @@ -1200,6 +1200,12 @@ vu_set_vring_num_exec(VuDev *dev, VhostUserMsg *vmsg) =20 DPRINT("State.index: %u\n", index); DPRINT("State.num: %u\n", num); + + if (index >=3D dev->max_queues) { + vu_panic(dev, "Invalid vring_num index: %u", index); + return false; + } + dev->vq[index].vring.num =3D num; =20 return false; @@ -1210,7 +1216,7 @@ vu_set_vring_addr_exec(VuDev *dev, VhostUserMsg *vmsg) { struct vhost_vring_addr addr =3D vmsg->payload.addr, *vra =3D &addr; unsigned int index =3D vra->index; - VuVirtq *vq =3D &dev->vq[index]; + VuVirtq *vq; =20 DPRINT("vhost_vring_addr:\n"); DPRINT(" index: %d\n", vra->index); @@ -1220,6 +1226,12 @@ vu_set_vring_addr_exec(VuDev *dev, VhostUserMsg *vms= g) DPRINT(" avail_user_addr: 0x%016" PRIx64 "\n", (uint64_t)vra->avai= l_user_addr); DPRINT(" log_guest_addr: 0x%016" PRIx64 "\n", (uint64_t)vra->log_= guest_addr); =20 + if (index >=3D dev->max_queues) { + vu_panic(dev, "Invalid vring_addr index: %u", index); + return false; + } + + vq =3D &dev->vq[index]; vq->vra =3D *vra; vq->vring.flags =3D vra->flags; vq->vring.log_guest_addr =3D vra->log_guest_addr; @@ -1256,6 +1268,12 @@ vu_set_vring_base_exec(VuDev *dev, VhostUserMsg *vms= g) =20 DPRINT("State.index: %u\n", index); DPRINT("State.num: %u\n", num); + + if (index >=3D dev->max_queues) { + vu_panic(dev, "Invalid vring_base index: %u", index); + return false; + } + dev->vq[index].shadow_avail_idx =3D dev->vq[index].last_avail_idx =3D = num; =20 return false; @@ -1267,6 +1285,14 @@ vu_get_vring_base_exec(VuDev *dev, VhostUserMsg *vms= g) unsigned int index =3D vmsg->payload.state.index; =20 DPRINT("State.index: %u\n", index); + + if (index >=3D dev->max_queues) { + vu_panic(dev, "Invalid vring_base index: %u", index); + vmsg->payload.state.num =3D 0; + vmsg->size =3D sizeof(vmsg->payload.state); + return true; + } + vmsg->payload.state.num =3D dev->vq[index].last_avail_idx; vmsg->size =3D sizeof(vmsg->payload.state); =20 --=20 MST