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

commit 01ca4f2d4f8350dd3ebe555b90e2e8d790a82609 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: 4006e3417b26 ("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 214829c32ed87bd0a9e1c1335861fd0ed8065135..7a2f262414ad416e37941c3070c5a368b662332b 100644 (file)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
@@ -308,7 +308,8 @@ 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 */