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c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1784100450; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=tyjuwjAxSkO1LIa98tG/BtwMCm/Bmc92Ql28vbDp5yI=; b=gQRTA/ufpxC90rCkSI843uHL9M1kfalwRQWTr1GYUclOd42xhNb27LwBEgwXwsSldW50IQ dQq5V3suJkFky8O0O3+KU3SnR6+jeXndBIvB1CZw/W/K3F8wZFXeBneXrlS8Auo7Cm6Bxu BkQDijEcMPbJlsQWgj/2Hj2xotPHK54= X-MC-Unique: DyIRPWt4P4i9J7vc0MY8sA-1 X-Mimecast-MFC-AGG-ID: DyIRPWt4P4i9J7vc0MY8sA_1784100447 From: marcandre.lureau@redhat.com To: qemu-devel@nongnu.org Cc: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= Subject: [PATCH] hw/display/qxl: validate monitors_config heads[] in phys2virt Date: Wed, 15 Jul 2026 11:27:22 +0400 Message-ID: <20260715072722.1643289-1-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 10.30.177.111 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=170.10.129.124; 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_H2=-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: 1784100499185158500 From: Marc-Andr=C3=A9 Lureau The qxl_phys2virt() call for guest_monitors_config only validates sizeof(QXLMonitorsConfig), which covers the fixed header (count and max_allowed) since commit 8efec0ef8bbc ("hw/display/qxl: Pass requested buffer size to qxl_phys2virt()"), but not the flexible array member heads[]. When count =3D=3D 1, heads[0] is accessed without its memory being validated, allowing a guest to cause an out-of-bounds read. Include sizeof(QXLHead) in the size passed to qxl_phys2virt() so that the first head entry is validated within the guest memory slot, preventing guest-visible memory reading. Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/4027 Reported-by: Tristan @TristanInSec Signed-off-by: Marc-Andre Lureau Reviewed-by: Philippe Mathieu-Daud=C3=A9 --- hw/display/qxl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/display/qxl.c b/hw/display/qxl.c index 74258afa582..3df796175c2 100644 --- a/hw/display/qxl.c +++ b/hw/display/qxl.c @@ -270,7 +270,7 @@ static void qxl_spice_monitors_config_async(PCIQXLDevic= e *qxl, int replay) } =20 cfg =3D qxl_phys2virt(qxl, qxl->guest_monitors_config, MEMSLOT_GROUP_G= UEST, - sizeof(QXLMonitorsConfig)); + sizeof(QXLMonitorsConfig) + sizeof(QXLHead)); if (cfg !=3D NULL && cfg->count =3D=3D 1) { qxl->guest_primary.resized =3D 1; qxl->guest_head0_width =3D cfg->heads[0].width; --=20 2.55.0