From 87a318f0b8758f940a316831a77b6ebebca42b19 Mon Sep 17 00:00:00 2001
From: Jon Maloy <jmaloy@redhat.com>
Date: Wed, 4 May 2022 10:35:17 -0400
Subject: [PATCH 3/3] ui/cursor: fix integer overflow in cursor_alloc
 (CVE-2021-4206)
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RH-Author: Jon Maloy <jmaloy@redhat.com>
RH-MergeRequest: 180: ui/cursor: fix integer overflow in cursor_alloc (CVE-2021-4206)
RH-Commit: [1/1] 7ad711347bc6248dc5aefa45401ca74448dee5e5 (jmaloy/qemu-kvm)
RH-Bugzilla: 2040734
RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
RH-Acked-by: Mauro Matteo Cascella <None>
RH-Acked-by: Gerd Hoffmann <kraxel@redhat.com>

BZ: https://bugzilla.redhat.com/show_bug.cgi?id=2040734
Upstream: Merged
CVE: CVE-2021-4206

commit fa892e9abb728e76afcf27323ab29c57fb0fe7aa
Author: Mauro Matteo Cascella <mcascell@redhat.com>
Date:   Thu Apr 7 10:17:12 2022 +0200

    ui/cursor: fix integer overflow in cursor_alloc (CVE-2021-4206)

    Prevent potential integer overflow by limiting 'width' and 'height' to
    512x512. Also change 'datasize' type to size_t. Refer to security
    advisory https://starlabs.sg/advisories/22-4206/ for more information.

    Fixes: CVE-2021-4206
    Signed-off-by: Mauro Matteo Cascella <mcascell@redhat.com>
    Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
    Message-Id: <20220407081712.345609-1-mcascell@redhat.com>
    Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

(cherry picked from commit fa892e9abb728e76afcf27323ab29c57fb0fe7aa)
Signed-off-by: Jon Maloy <jmaloy@redhat.com>
---
 hw/display/qxl-render.c | 7 +++++++
 hw/display/vmware_vga.c | 2 ++
 ui/cursor.c             | 8 +++++++-
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/hw/display/qxl-render.c b/hw/display/qxl-render.c
index 237ed293ba..ca217004bf 100644
--- a/hw/display/qxl-render.c
+++ b/hw/display/qxl-render.c
@@ -247,6 +247,13 @@ static QEMUCursor *qxl_cursor(PCIQXLDevice *qxl, QXLCursor *cursor,
     size_t size;
 
     c = cursor_alloc(cursor->header.width, cursor->header.height);
+
+    if (!c) {
+        qxl_set_guest_bug(qxl, "%s: cursor %ux%u alloc error", __func__,
+                cursor->header.width, cursor->header.height);
+        goto fail;
+    }
+
     c->hot_x = cursor->header.hot_spot_x;
     c->hot_y = cursor->header.hot_spot_y;
     switch (cursor->header.type) {
diff --git a/hw/display/vmware_vga.c b/hw/display/vmware_vga.c
index e2969a6c81..2b81d6122f 100644
--- a/hw/display/vmware_vga.c
+++ b/hw/display/vmware_vga.c
@@ -509,6 +509,8 @@ static inline void vmsvga_cursor_define(struct vmsvga_state_s *s,
     int i, pixels;
 
     qc = cursor_alloc(c->width, c->height);
+    assert(qc != NULL);
+
     qc->hot_x = c->hot_x;
     qc->hot_y = c->hot_y;
     switch (c->bpp) {
diff --git a/ui/cursor.c b/ui/cursor.c
index 1d62ddd4d0..835f0802f9 100644
--- a/ui/cursor.c
+++ b/ui/cursor.c
@@ -46,6 +46,8 @@ static QEMUCursor *cursor_parse_xpm(const char *xpm[])
 
     /* parse pixel data */
     c = cursor_alloc(width, height);
+    assert(c != NULL);
+
     for (pixel = 0, y = 0; y < height; y++, line++) {
         for (x = 0; x < height; x++, pixel++) {
             idx = xpm[line][x];
@@ -91,7 +93,11 @@ QEMUCursor *cursor_builtin_left_ptr(void)
 QEMUCursor *cursor_alloc(int width, int height)
 {
     QEMUCursor *c;
-    int datasize = width * height * sizeof(uint32_t);
+    size_t datasize = width * height * sizeof(uint32_t);
+
+    if (width > 512 || height > 512) {
+        return NULL;
+    }
 
     c = g_malloc0(sizeof(QEMUCursor) + datasize);
     c->width  = width;
-- 
2.35.1