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bh=r4OySs/MlLnhS4aHMYzmzTaVrGn4YZ/1dItiYGgCXgg=; b=DWxBeGIcLpduop4V8vC2A4CDQjRBnYyy3ZE1UnSuzS4PeUdnsaBjbAiZgGcSo5tW611c6i QMvwR3O5+L5Xvt86+aAPzbB8wnWPsK7YnwLHb/gikibBXsICxK0ISMfb8QyM8eyHNVVd90 EE22eO9qLINKF+ImvZJC0KsB6ilBx0M= X-MC-Unique: 7YkuCCHPP2CSqpJKk4sd0A-1 From: Jason Wang To: qemu-devel@nongnu.org Cc: Peter Maydell , Francisco Iglesias , Jason Wang Subject: [PULL V2 17/17] net/tap: Avoid variable-length array Date: Mon, 18 Sep 2023 16:31:32 +0800 Message-Id: <20230918083132.55423-18-jasowang@redhat.com> In-Reply-To: <20230918083132.55423-1-jasowang@redhat.com> References: <20230918083132.55423-1-jasowang@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 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=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=jasowang@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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=0.001, RCVD_IN_MSPIKE_WL=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: 2.1.29 Precedence: list List-Id: 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: 1695026141341100001 Content-Type: text/plain; charset="utf-8" From: Peter Maydell Use a heap allocation instead of a variable length array in tap_receive_iov(). The codebase has very few VLAs, and if we can get rid of them all we can make the compiler error on new additions. This is a defensive measure against security bugs where an on-stack dynamic allocation isn't correctly size-checked (e.g. CVE-2021-3527). Signed-off-by: Peter Maydell Reviewed-by: Francisco Iglesias Signed-off-by: Jason Wang --- net/tap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/tap.c b/net/tap.c index bcea8d0..c23d032 100644 --- a/net/tap.c +++ b/net/tap.c @@ -118,10 +118,11 @@ static ssize_t tap_receive_iov(NetClientState *nc, co= nst struct iovec *iov, { TAPState *s =3D DO_UPCAST(TAPState, nc, nc); const struct iovec *iovp =3D iov; - struct iovec iov_copy[iovcnt + 1]; + g_autofree struct iovec *iov_copy =3D NULL; struct virtio_net_hdr_mrg_rxbuf hdr =3D { }; =20 if (s->host_vnet_hdr_len && !s->using_vnet_hdr) { + iov_copy =3D g_new(struct iovec, iovcnt + 1); iov_copy[0].iov_base =3D &hdr; iov_copy[0].iov_len =3D s->host_vnet_hdr_len; memcpy(&iov_copy[1], iov, iovcnt * sizeof(*iov)); --=20 2.7.4