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From 87a318f0b8758f940a316831a77b6ebebca42b19 Mon Sep 17 00:00:00 2001
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From: Jon Maloy <jmaloy@redhat.com>
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Date: Wed, 4 May 2022 10:35:17 -0400
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Subject: [PATCH 3/3] ui/cursor: fix integer overflow in cursor_alloc
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 (CVE-2021-4206)
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Jon Maloy <jmaloy@redhat.com>
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RH-MergeRequest: 180: ui/cursor: fix integer overflow in cursor_alloc (CVE-2021-4206)
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RH-Commit: [1/1] 7ad711347bc6248dc5aefa45401ca74448dee5e5 (jmaloy/qemu-kvm)
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RH-Bugzilla: 2040734
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RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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RH-Acked-by: Mauro Matteo Cascella <None>
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RH-Acked-by: Gerd Hoffmann <kraxel@redhat.com>
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BZ: https://bugzilla.redhat.com/show_bug.cgi?id=2040734
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Upstream: Merged
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CVE: CVE-2021-4206
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commit fa892e9abb728e76afcf27323ab29c57fb0fe7aa
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Author: Mauro Matteo Cascella <mcascell@redhat.com>
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Date:   Thu Apr 7 10:17:12 2022 +0200
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    ui/cursor: fix integer overflow in cursor_alloc (CVE-2021-4206)
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    Prevent potential integer overflow by limiting 'width' and 'height' to
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    512x512. Also change 'datasize' type to size_t. Refer to security
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    advisory https://starlabs.sg/advisories/22-4206/ for more information.
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    Fixes: CVE-2021-4206
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    Signed-off-by: Mauro Matteo Cascella <mcascell@redhat.com>
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    Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
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    Message-Id: <20220407081712.345609-1-mcascell@redhat.com>
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    Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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(cherry picked from commit fa892e9abb728e76afcf27323ab29c57fb0fe7aa)
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Signed-off-by: Jon Maloy <jmaloy@redhat.com>
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---
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 hw/display/qxl-render.c | 7 +++++++
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 hw/display/vmware_vga.c | 2 ++
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 ui/cursor.c             | 8 +++++++-
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 3 files changed, 16 insertions(+), 1 deletion(-)
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diff --git a/hw/display/qxl-render.c b/hw/display/qxl-render.c
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index 237ed293ba..ca217004bf 100644
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--- a/hw/display/qxl-render.c
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+++ b/hw/display/qxl-render.c
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@@ -247,6 +247,13 @@ static QEMUCursor *qxl_cursor(PCIQXLDevice *qxl, QXLCursor *cursor,
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     size_t size;
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     c = cursor_alloc(cursor->header.width, cursor->header.height);
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+
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+    if (!c) {
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+        qxl_set_guest_bug(qxl, "%s: cursor %ux%u alloc error", __func__,
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+                cursor->header.width, cursor->header.height);
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+        goto fail;
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+    }
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+
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     c->hot_x = cursor->header.hot_spot_x;
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     c->hot_y = cursor->header.hot_spot_y;
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     switch (cursor->header.type) {
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diff --git a/hw/display/vmware_vga.c b/hw/display/vmware_vga.c
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index e2969a6c81..2b81d6122f 100644
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--- a/hw/display/vmware_vga.c
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+++ b/hw/display/vmware_vga.c
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@@ -509,6 +509,8 @@ static inline void vmsvga_cursor_define(struct vmsvga_state_s *s,
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     int i, pixels;
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     qc = cursor_alloc(c->width, c->height);
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+    assert(qc != NULL);
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+
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     qc->hot_x = c->hot_x;
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     qc->hot_y = c->hot_y;
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     switch (c->bpp) {
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diff --git a/ui/cursor.c b/ui/cursor.c
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index 1d62ddd4d0..835f0802f9 100644
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--- a/ui/cursor.c
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+++ b/ui/cursor.c
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@@ -46,6 +46,8 @@ static QEMUCursor *cursor_parse_xpm(const char *xpm[])
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     /* parse pixel data */
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     c = cursor_alloc(width, height);
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+    assert(c != NULL);
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+
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     for (pixel = 0, y = 0; y < height; y++, line++) {
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         for (x = 0; x < height; x++, pixel++) {
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             idx = xpm[line][x];
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@@ -91,7 +93,11 @@ QEMUCursor *cursor_builtin_left_ptr(void)
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 QEMUCursor *cursor_alloc(int width, int height)
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 {
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     QEMUCursor *c;
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-    int datasize = width * height * sizeof(uint32_t);
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+    size_t datasize = width * height * sizeof(uint32_t);
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+
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+    if (width > 512 || height > 512) {
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+        return NULL;
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+    }
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     c = g_malloc0(sizeof(QEMUCursor) + datasize);
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     c->width  = width;
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-- 
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2.35.1
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