drm/vmwgfx: Validate the box size for the snooped cursor

commit 4cf949c7fafe21e085a4ee386bb2dade9067316e upstream.

Invalid userspace dma surface copies could potentially overflow
the memcpy from the surface to the snooped image leading to crashes.
To fix it the dimensions of the copybox have to be validated
against the expected size of the snooped cursor.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Fixes: 2ac863719e51 ("vmwgfx: Snoop DMA transfers with non-covering sizes")
Cc: <stable@vger.kernel.org> # v3.2+
Reviewed-by: Michael Banack <banackm@vmware.com>
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221026031936.1004280-1-zack@kde.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
index ff2f735bbe7a08df1951e21759d56da8a8fa658f..5c7dc411b1804dd1f4b885ec6c46b25f491d1d3b 100644 (file)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
@@ -309,7 +309,8 @@ void vmw_kms_cursor_snoop(struct vmw_surface *srf,
        if (cmd->dma.guest.ptr.offset % PAGE_SIZE ||
            box->x != 0    || box->y != 0    || box->z != 0    ||
            box->srcx != 0 || box->srcy != 0 || box->srcz != 0 ||
-           box->d != 1    || box_count != 1) {
+           box->d != 1    || box_count != 1 ||
+           box->w > 64 || box->h > 64) {
                /* TODO handle none page aligned offsets */
                /* TODO handle more dst & src != 0 */
                /* TODO handle more then one copy */