FAILED: patch "[PATCH] drm/vmwgfx: reject DX_BIND_QUERY without a DX context" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-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 <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 55ec09c9ce10b1272802c7ab6c1be2ea0dbc68db
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026080554-crevice-snuff-ec4b@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 55ec09c9ce10b1272802c7ab6c1be2ea0dbc68db Mon Sep 17 00:00:00 2001
From: Zack Rusin <[email protected]>
Date: Tue, 5 May 2026 18:22:23 -0400
Subject: [PATCH] drm/vmwgfx: reject DX_BIND_QUERY without a DX context

vmw_cmd_dx_bind_query() unconditionally dereferences sw_context->dx_ctx_node->ctx. Userspace can trigger a NULL pointer dereference from any render-node fd by submitting an execbuf with dx_context_handle == SVGA3D_INVALID_ID and a SVGA_3D_CMD_DX_BIND_QUERY opcode in the command stream: dx_ctx_node is left NULL and the kernel oopses on the assignment. The same NULL is then re-read in vmw_resources_reserve() via vmw_context_get_dx_query_mob().

All sibling DX handlers fail-close on a missing dx_ctx_node using VMW_GET_CTX_NODE(). Use the same pattern here, returning -EINVAL up front before any relocation state is published.

index e1f18020170a..b07f052474d0 100644
@@ -1272,9 +1272,13 @@ static int vmw_cmd_dx_bind_query(struct vmw_private *dev_priv,
 				 SVGA3dCmdHeader *header)
 {
 	VMW_DECLARE_CMD_VAR(*cmd, SVGA3dCmdDXBindQuery);
+	struct vmw_ctx_validation_info *ctx_node = VMW_GET_CTX_NODE(sw_context);
 	struct vmw_bo *vmw_bo;
 	int ret;
 
+	if (!ctx_node)
+		return -EINVAL;
+
 	cmd = container_of(header, typeof(*cmd), header);
 
 	/*

@@ -1288,7 +1292,7 @@ static int vmw_cmd_dx_bind_query(struct vmw_private *dev_priv,
 		return ret;
 
 	sw_context->dx_query_mob = vmw_bo;
-	sw_context->dx_query_ctx = sw_context->dx_ctx_node->ctx;
+	sw_context->dx_query_ctx = ctx_node->ctx;
 	return 0;
 }