Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 16FEEC433EF for ; Tue, 16 Nov 2021 02:27:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0243960F38 for ; Tue, 16 Nov 2021 02:27:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344759AbhKPCaT (ORCPT ); Mon, 15 Nov 2021 21:30:19 -0500 Received: from mail.kernel.org ([198.145.29.99]:48804 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236909AbhKORQh (ORCPT ); Mon, 15 Nov 2021 12:16:37 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0E0AE63247; Mon, 15 Nov 2021 17:12:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1636996360; bh=EjAYMVikh+ar3WB5M1uox3DB/K28A+dIc56LbYZC5DM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GztvzWEd8Zllw/zNeP9zQlS9QmJUiqUr0DATQWP54H9/yS/CoqNzgpIh+irL58eSf pfVq0FzBy123DP4HSuPoVqJmo3cssO+Ryauod0W0qkHyD7IDz23MC2LZ0OvQst2Tn6 TcPZp3DBL3O/eFtPweiEv0Qb+7G0U4OtRHlJi174= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Charan Teja Reddy , =?UTF-8?q?Christian=20K=C3=B6nig?= , Sasha Levin Subject: [PATCH 5.4 112/355] dma-buf: WARN on dmabuf release with pending attachments Date: Mon, 15 Nov 2021 18:00:36 +0100 Message-Id: <20211115165317.427654852@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211115165313.549179499@linuxfoundation.org> References: <20211115165313.549179499@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Charan Teja Reddy [ Upstream commit f492283b157053e9555787262f058ae33096f568 ] It is expected from the clients to follow the below steps on an imported dmabuf fd: a) dmabuf = dma_buf_get(fd) // Get the dmabuf from fd b) dma_buf_attach(dmabuf); // Clients attach to the dmabuf o Here the kernel does some slab allocations, say for dma_buf_attachment and may be some other slab allocation in the dmabuf->ops->attach(). c) Client may need to do dma_buf_map_attachment(). d) Accordingly dma_buf_unmap_attachment() should be called. e) dma_buf_detach () // Clients detach to the dmabuf. o Here the slab allocations made in b) are freed. f) dma_buf_put(dmabuf) // Can free the dmabuf if it is the last reference. Now say an erroneous client failed at step c) above thus it directly called dma_buf_put(), step f) above. Considering that it may be the last reference to the dmabuf, buffer will be freed with pending attachments left to the dmabuf which can show up as the 'memory leak'. This should at least be reported as the WARN(). Signed-off-by: Charan Teja Reddy Reviewed-by: Christian König Link: https://patchwork.freedesktop.org/patch/msgid/1627043468-16381-1-git-send-email-charante@codeaurora.org Signed-off-by: Christian König Signed-off-by: Sasha Levin --- drivers/dma-buf/dma-buf.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 758de0e9b2ddc..16bbc9bc9e6d1 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -79,6 +79,7 @@ static void dma_buf_release(struct dentry *dentry) if (dmabuf->resv == (struct dma_resv *)&dmabuf[1]) dma_resv_fini(dmabuf->resv); + WARN_ON(!list_empty(&dmabuf->attachments)); module_put(dmabuf->owner); kfree(dmabuf->name); kfree(dmabuf); -- 2.33.0