From nobody Mon Sep 28 02:00:07 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=none dis=none) header.from=gmail.com ARC-Seal: i=1; a=rsa-sha256; t=1785250028; cv=none; d=zohomail.com; s=zohoarc; b=jaLYya05dnchjVH2pDQfkc+f0Y9ge9nIieakvBi3q8fdzy3CYrER34gfmghCu+2sf7uKewMEXttkBo1pUszp7WWZL/vfs147+i3M5lINGquEFJeHlMVkUDlXuJRqAL0PKUcGwQIUhXz/ZDCU5vGAVoYLPBj3YONgF7JqUH1f66I= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1785250028; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=U2zaWvTtl44HTglvhMoWXik3ygFdc89/lqZhyO6KZ4o=; b=ljLS7g0wcyaRoYU0sHQT/6tvhG5MewWMGQ899LyS4wQIHblsQN/jV7CGEfQxd135aWLkPgQu6y2y36iSZ49GIt7Wl7Zy6g/XMO4WpLPjkI7vYAXKzZyFDy56Irar1mPn922oaAdSuEa2qk4Dgm00o8yjfa9vtv3SPzWTiGF9Pnw= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=none dis=none) Return-Path: Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1785250028050728.4243328536888; Tue, 28 Jul 2026 07:47:08 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1woj4r-0005Qj-CJ; Tue, 28 Jul 2026 10:46:43 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1woibw-00085I-D4 for qemu-devel@nongnu.org; Tue, 28 Jul 2026 10:16:48 -0400 Received: from mail-pj1-x102e.google.com ([2607:f8b0:4864:20::102e]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1woibu-0004pC-R8 for qemu-devel@nongnu.org; Tue, 28 Jul 2026 10:16:48 -0400 Received: by mail-pj1-x102e.google.com with SMTP id 98e67ed59e1d1-38511175ad3so2719317a91.2 for ; Tue, 28 Jul 2026 07:16:46 -0700 (PDT) Received: from [127.0.1.1] ([49.43.137.199]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-314bc413766sm45998740eec.8.2026.07.28.07.16.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jul 2026 07:16:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1785248205; x=1785853005; darn=nongnu.org; h=cc:to:message-id:content-transfer-encoding:content-type :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to:content-type; bh=U2zaWvTtl44HTglvhMoWXik3ygFdc89/lqZhyO6KZ4o=; b=fmdlQR1EnIE3B+zwkQmp83zy+hXvADD9xWkYqIS2ASfRoJY+E29cvEy4FmBGjtTSWi dwRq7DFOfnOl5KFfNSv0eH5zbFzbEiJbqY+iuQ4ndQtDPIBwXTaob4UrDLC7+XJxKRuU gquFCRriNlRUTN7am+WzKLd6OjbcX/cklYVVokWOSPcqDSeSX6j/QiHxVkvyXk60Ksas KGgr/wC2BGeldzprWU9QxWmyrFQkXWenT1wFGYNxTBJ3e3uSAw38ohjv6DM/87BFjFo9 gXBNB/I1jgbw57JzMdR4vQTz0gRhzxHirMlO3PqDRXK1j/DeQcRgmfugX0RCrE+AZvwo nIJA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785248205; x=1785853005; h=cc:to:message-id:content-transfer-encoding:content-type :mime-version:subject:date:from:x-gm-gg:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to:content-type; bh=U2zaWvTtl44HTglvhMoWXik3ygFdc89/lqZhyO6KZ4o=; b=ilczNTZ95qk7YdcTpxVhdpkRaDvikeMDwMwHnM7CzkSSz+KNiW+v/q6Qu5StvL+sB5 vEu7KFJjtsOUioGGokgzcgQ4ccIHzpb4FEouHF2007L6lViFYxnuJt40PxHQKB10UG2/ iqz6/BL8kzo3Vu8/nHBkdrs+0laoWIOHc+DCVq4AS825MGYs+1copWwgig7abQuSpCY0 /oi6Jn4hHdzHexnki81msmzs0ei4eyob14O/igWHkF2nT/80FQP75WTr3mKuRzl7uUUy TU9xUGr1DDnbsUvzbhb9Dh/rYfW5Ms/46qEPgVub4FuXyNBePbYGY7CiaesWU+ax+Xpr 8PoQ== X-Gm-Message-State: AOJu0YwT+CO6PZUe+8b4JOUO5JzVgdg7/QkhvbMex1Q0K7I5rsrajtWy aFCSHk+c59yxVFmDISyZCwASvJorF90koMjwWYm0cROZznNOH1kckGLanMZCpxyj X-Gm-Gg: AR+sD12BXC58HSc2OLFfmfRh7mm2OVjmY71JFcpN29zJtqxRbXKkWe1vnOcUWSGbFBI yx7CZee5dBNn7JHzoU0XirvqTcRHlmKHT8+D+lx2zdVgictXnZc1jTm9h7u1Q5cXTXv06HITd/L updMp/ZWSRGWw3cjs/Mpr4TOPjiS30C1FdbkGmufAXtJ4s9IT/AIcjv8cFDX2UM4/jINfzN9OCj 0o1vsBGEdUsRrrRdBSyL68dpulbp0De6+hrIiwSk3PvFJUh3vw/SNduFco3GbHj84J7/f2EIL1F 5dpx90vCnuTHIsKbqkzMsBEPcBgBLjwwf5782+/KLkugqHZN6mQytmG0ml4KVTFf2iJlTBvBn9f hWNtPYQI5xstHJ07LQoB0Mt3eZDv2BHlnqnMbbKr4tx7DhC8eA5wcP/dP1cvhSqJ5hMO02VL/lL eXbndsvoshVV9t+ZJ24FdbxQ== X-Received: by 2002:a17:90b:6cb:b0:38e:e0b:320d with SMTP id 98e67ed59e1d1-38f6a480a61mr2844239a91.41.1785248204865; Tue, 28 Jul 2026 07:16:44 -0700 (PDT) From: Ankur Saini Date: Tue, 28 Jul 2026 19:46:26 +0530 Subject: [PATCH] virtio-gpu: reject requests with short/truncated control headers MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260728-virtio-gpu-short-header-v1-1-af19a00b100d@gmail.com> X-B4-Tracking: v=1; b=H4sIAAAAAAAC/x3MMQqAMAxA0atIZgNaxIpXEYdg0zaLlVRFkN7d4 viG/1/IrMIZ5uYF5VuypL2ibxvYIu2BUVw1mM6MnTUT3qKnJAzHhTkmPTEyOVYc7EjUO+LBW6j 1oezl+c/LWsoHVf5LamkAAAA= X-Change-ID: 20260728-virtio-gpu-short-header-476aa1dae4f7 To: qemu-devel@nongnu.org Cc: =?utf-8?q?Alex_Benn=C3=A9e?= , Akihiko Odaki , Dmitry Osipenko , "Michael S. Tsirkin" , Ankur Saini X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1785248201; l=2028; i=ankur98saini@gmail.com; s=20260728; h=from:subject:message-id; bh=qIndgFbaTJljNIzm/aezZhwlfPR+k3VUJ5+5SD8sUjI=; b=tSzKEL36AkFeodx7ZrcwAfiJshueff6QoTSW0gR69VBK97pWFnp3ltpu+yDX5KvFQ95loLXj4 zryVNmARLhODkBi+NtIzxUzhuuTVHaaPG+ub1FATGV3LQk6wB9BIIJw X-Developer-Key: i=ankur98saini@gmail.com; a=ed25519; pk=fiA1ENLrWfuTIKes9f/fn/hIbq1fqEHYxopa8LdM/8s= 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=2607:f8b0:4864:20::102e; envelope-from=ankur98saini@gmail.com; helo=mail-pj1-x102e.google.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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-Mailman-Approved-At: Tue, 28 Jul 2026 10:46:14 -0400 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 @gmail.com) X-ZM-MESSAGEID: 1785250029514158500 A control request shorter than virtio_gpu_ctrl_hdr can leave cmd_hdr partially initialized. If the supplied bytes set the fence flag, stale fence metadata may later be returned to the guest. Validate the common header length before dispatch. Clear cmd_hdr and complete malformed requests with ERR_INVALID_PARAMETER so stale fields cannot reach the response. Fixes: CVE-2026-18054 Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/4094 Reported-by: Ankur Saini Signed-off-by: Ankur Saini Reviewed-by: Akihiko Odaki Reviewed-by: Marc-Andr=C3=A9 Lureau --- A control request shorter than virtio_gpu_ctrl_hdr can leave cmd_hdr partially initialized. If the supplied bytes set the fence flag, stale fence metadata may later be returned to the guest. Validate the common header length before dispatch. Clear cmd_hdr and complete malformed requests with ERR_INVALID_PARAMETER so stale fields cannot reach the response. --- hw/display/virtio-gpu.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c index 4d46a4eb10..15a845eff6 100644 --- a/hw/display/virtio-gpu.c +++ b/hw/display/virtio-gpu.c @@ -1105,8 +1105,14 @@ void virtio_gpu_process_cmdq(VirtIOGPU *g) break; } =20 - /* process command */ - vgc->process_cmd(g, cmd); + if (unlikely(iov_size(cmd->elem.out_sg, cmd->elem.out_num) < + sizeof(cmd->cmd_hdr))) { + memset(&cmd->cmd_hdr, 0, sizeof(cmd->cmd_hdr)); + virtio_gpu_ctrl_response_nodata( + g, cmd, VIRTIO_GPU_RESP_ERR_INVALID_PARAMETER); + } else { + vgc->process_cmd(g, cmd); + } =20 /* command suspended */ if (!cmd->finished && !(cmd->cmd_hdr.flags & VIRTIO_GPU_FLAG_FENCE= )) { --- base-commit: 299e7557ed15a9a325620698add379a3ce2d1d95 change-id: 20260728-virtio-gpu-short-header-476aa1dae4f7 Best regards, --=20 Ankur Saini