From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1742EC10F0E for ; Mon, 15 Apr 2019 11:52:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DD1A42073F for ; Mon, 15 Apr 2019 11:52:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mev.co.uk header.i=@mev.co.uk header.b="cJiD5z+X" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727342AbfDOLwm (ORCPT ); Mon, 15 Apr 2019 07:52:42 -0400 Received: from smtp112.iad3a.emailsrvr.com ([173.203.187.112]:54626 "EHLO smtp112.iad3a.emailsrvr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726182AbfDOLwm (ORCPT ); Mon, 15 Apr 2019 07:52:42 -0400 Received: from smtp7.relay.iad3a.emailsrvr.com (localhost [127.0.0.1]) by smtp7.relay.iad3a.emailsrvr.com (SMTP Server) with ESMTP id D27C43A1B; Mon, 15 Apr 2019 07:52:40 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=mev.co.uk; s=20190130-41we5z8j; t=1555329160; bh=bDoBB/miubeqrsxxvGhYDLsTOVsh4BOlQkap4COlMbk=; h=From:To:Subject:Date:From; b=cJiD5z+X+PHOT3G9iWIILh/ONH7PW6blACeq+i2mKZrBEq3/Q0mlUc7tinVDQZyc/ QzzDtq5S/lg/yxcV+mPlE4Zbd1ZMcLRdCBChxNCUcVBwAy8itPrUX8MxVwloLdoXma 0GKXIR1rp7pU4ruO+4LhjLomSV9f/XFxoX/tGRuc= X-Auth-ID: abbotti@mev.co.uk Received: by smtp7.relay.iad3a.emailsrvr.com (Authenticated sender: abbotti-AT-mev.co.uk) with ESMTPSA id 15FA62BA8; Mon, 15 Apr 2019 07:52:39 -0400 (EDT) X-Sender-Id: abbotti@mev.co.uk Received: from ian-deb.inside.mev.co.uk (remote.quintadena.com [81.133.34.160]) (using TLSv1.2 with cipher DHE-RSA-AES128-GCM-SHA256) by 0.0.0.0:465 (trex/5.7.12); Mon, 15 Apr 2019 07:52:40 -0400 From: Ian Abbott To: devel@driverdev.osuosl.org Cc: Greg Kroah-Hartman , Ian Abbott , H Hartley Sweeten , linux-kernel@vger.kernel.org Subject: [PATCH v2 2/2] staging: comedi: vmk80xx: Fix possible double-free of ->usb_rx_buf Date: Mon, 15 Apr 2019 12:52:30 +0100 Message-Id: <20190415115230.7288-1-abbotti@mev.co.uk> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190415111015.8257-3-abbotti@mev.co.uk> References: <20190415111015.8257-3-abbotti@mev.co.uk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org `vmk80xx_alloc_usb_buffers()` is called from `vmk80xx_auto_attach()` to allocate RX and TX buffers for USB transfers. It allocates `devpriv->usb_rx_buf` followed by `devpriv->usb_tx_buf`. If the allocation of `devpriv->usb_tx_buf` fails, it frees `devpriv->usb_rx_buf`, leaving the pointer set dangling, and returns an error. Later, `vmk80xx_detach()` will be called from the core comedi module code to clean up. `vmk80xx_detach()` also frees both `devpriv->usb_rx_buf` and `devpriv->usb_tx_buf`, but `devpriv->usb_rx_buf` may have already been freed, leading to a double-free error. Fix it by removing the call to `kfree(devpriv->usb_rx_buf)` from `vmk80xx_alloc_usb_buffers()`, relying on `vmk80xx_detach()` to free the memory. Signed-off-by: Ian Abbott --- v2: Fix commit message because it incorrectly indicated that the call to `kfree()` was being removed from `vmk80xx_auto_attach()`, not `vmk80xx_alloc_usb_buffers(). --- drivers/staging/comedi/drivers/vmk80xx.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/staging/comedi/drivers/vmk80xx.c b/drivers/staging/comedi/drivers/vmk80xx.c index b035d662390b..65dc6c51037e 100644 --- a/drivers/staging/comedi/drivers/vmk80xx.c +++ b/drivers/staging/comedi/drivers/vmk80xx.c @@ -682,10 +682,8 @@ static int vmk80xx_alloc_usb_buffers(struct comedi_device *dev) size = usb_endpoint_maxp(devpriv->ep_tx); devpriv->usb_tx_buf = kzalloc(size, GFP_KERNEL); - if (!devpriv->usb_tx_buf) { - kfree(devpriv->usb_rx_buf); + if (!devpriv->usb_tx_buf) return -ENOMEM; - } return 0; } -- 2.20.1