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

Origin: https://git.kernel.org/linus/4cf949c7fafe21e085a4ee386bb2dade9067316e
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2022-36280

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
Gbp-Pq: Topic bugfix/x86
Gbp-Pq: Name drm-vmwgfx-Validate-the-box-size-for-the-snooped-cur.patch

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
index e58112997c88136e4ecce5c238e99d366f2f5b6c..0e963fd7db17e73ffb1bfe7deac81843bd08b908 100644 (file)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
@@ -182,7 +182,8 @@ 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 */