drm/xe: Fix dma-buf attachment leak in xe_gem_prime_import()

commit 111ab67 upstream.

When xe_dma_buf_init_obj() fails, the attachment from
dma_buf_dynamic_attach() is not detached. Add dma_buf_detach() before
returning the error. Note: we cannot use goto out_err here because
xe_dma_buf_init_obj() already frees bo on failure, and out_err would
double-free it.

Fixes: dd08ebf ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4.6
Reviewed-by: Mattheq Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20260408175255.3402838-5-shuicheng.lin@intel.com
Signed-off-by: Shuicheng Lin <shuicheng.lin@intel.com>
(cherry picked from commit a828eb1)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: ShuichengLin

drivers/gpu/drm/xe/xe_dma_buf.c

@@ -299,12 +299,15 @@ struct drm_gem_object *xe_gem_prime_import(struct drm_device *dev,
 		goto out_err;
 	}
 
-	/* Errors here will take care of freeing the bo. */
+	/*
+	 * xe_dma_buf_init_obj() takes ownership of bo on both success
+	 * and failure, so we must not touch bo after this call.
+	 */
 	obj = xe_dma_buf_init_obj(dev, bo, dma_buf);
-	if (IS_ERR(obj))
+	if (IS_ERR(obj)) {
+		dma_buf_detach(dma_buf, attach);
 		return obj;
-
-
+	}
 	get_dma_buf(dma_buf);
 	obj->import_attach = attach;
 	return obj;