drm/vmwgfx: Fix Use-after-free in validation

Nodes stored in the validation duplicates hashtable come from an arena
allocator that is cleared at the end of vmw_execbuf_process. All nodes
are expected to be cleared in vmw_validation_drop_ht but this node escaped
because its resource was destroyed prematurely.

Fixes: 64ad2abfe9a6 ("drm/vmwgfx: Adapt validation code for reference-free lookups")
Reported-by: Kuzey Arda Bulut <kuzeyardabulut@gmail.com>
Signed-off-by: Ian Forbes <ian.forbes@broadcom.com>
Reviewed-by: Zack Rusin <zack.rusin@broadcom.com>
Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Link: https://lore.kernel.org/r/20250926195427.1405237-1-ian.forbes@broadcom.com

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_validation.c b/drivers/gpu/drm/vmwgfx/vmwgfx_validation.c
index 7ee93e7191c7fad1c62fb7cfe719f01e7d6828b8..4d0fb71f621110e6af7e7d83ee5643d98c3bf744 100644 (file)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_validation.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_validation.c
@@ -308,8 +308,10 @@ int vmw_validation_add_resource(struct vmw_validation_context *ctx,
                hash_add_rcu(ctx->sw_context->res_ht, &node->hash.head, node->hash.key);
        }
        node->res = vmw_resource_reference_unless_doomed(res);
-       if (!node->res)
+       if (!node->res) {
+               hash_del_rcu(&node->hash.head);
                return -ESRCH;
+       }
 
        node->first_usage = 1;
        if (!res->dev_priv->has_mob) {