The patch below does not apply to the 4.2-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From ed7d78b2da32198ca4c70172e3b63c6b3e2c570b Mon Sep 17 00:00:00 2001 From: Thomas Hellstrom <thellstrom@xxxxxxxxxx> Date: Mon, 12 Oct 2015 01:49:39 -0700 Subject: [PATCH] drm/vmwgfx: Fix kernel NULL pointer dereference on older hardware The commit "drm/vmwgfx: Fix up user_dmabuf refcounting", while fixing a kernel crash introduced a NULL pointer dereference on older hardware. Fix this. Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Thomas Hellstrom <thellstrom@xxxxxxxxxx> Reviewed-by: Sinclair Yeh <syeh@xxxxxxxxxx> Reviewed-by: Brian Paul <brianp@xxxxxxxxxx> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c index 64b50409fa07..03f63c749c02 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c @@ -657,7 +657,8 @@ static void vmw_user_surface_base_release(struct ttm_base_object **p_base) struct vmw_resource *res = &user_srf->srf.res; *p_base = NULL; - ttm_base_object_unref(&user_srf->backup_base); + if (user_srf->backup_base) + ttm_base_object_unref(&user_srf->backup_base); vmw_resource_unreference(&res); } -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html