From 9f22893adcb02580aee5968f32baa2cd109b3ec2 Mon Sep 17 00:00:00 2001
From: Li Qiang <liq3ea@163.com>
Date: Sat, 15 May 2021 20:04:02 -0700
Subject: [PATCH] vhost-user-gpu: fix OOB write in 'virgl_cmd_get_capset'
 (CVE-2021-3546)
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If 'virgl_cmd_get_capset' set 'max_size' to 0,
the 'virgl_renderer_fill_caps' will write the data after the 'resp'.
This patch avoid this by checking the returned 'max_size'.

virtio-gpu fix: abd7f08b23 ("display: virtio-gpu-3d: check
virgl capabilities max_size")

Fixes: CVE-2021-3546
Reported-by: Li Qiang <liq3ea@163.com>
Reviewed-by: Prasad J Pandit <pjp@fedoraproject.org>
Signed-off-by: Li Qiang <liq3ea@163.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20210516030403.107723-8-liq3ea@163.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Upstream-Status: Backport
CVE: CVE-2021-3546
Signed-off-by: Armin Kuster <akuster@mvista.com>

---
 contrib/vhost-user-gpu/virgl.c | 4 ++++
 1 file changed, 4 insertions(+)

Index: qemu-4.2.0/contrib/vhost-user-gpu/virgl.c
===================================================================
--- qemu-4.2.0.orig/contrib/vhost-user-gpu/virgl.c
+++ qemu-4.2.0/contrib/vhost-user-gpu/virgl.c
@@ -174,6 +174,10 @@ virgl_cmd_get_capset(VuGpu *g,
 
     virgl_renderer_get_cap_set(gc.capset_id, &max_ver,
                                &max_size);
+    if (!max_size) {
+        cmd->error = VIRTIO_GPU_RESP_ERR_INVALID_PARAMETER;
+        return;
+    }
     resp = g_malloc0(sizeof(*resp) + max_size);
 
     resp->hdr.type = VIRTIO_GPU_RESP_OK_CAPSET;