From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933074AbdC1MxD (ORCPT ); Tue, 28 Mar 2017 08:53:03 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:39384 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932969AbdC1Mwc (ORCPT ); Tue, 28 Mar 2017 08:52:32 -0400 Subject: Re: [PATCH] usb: gadget: pch_udc: don't update td->next after it has been released to the pool To: Felipe Balbi , Greg Kroah-Hartman , Andy Shevchenko , Michal Nazarewicz , "Gustavo A . R . Silva" , Iago Abal , Romain Perier , linux-usb@vger.kernel.org References: <20170328122850.18819-1-colin.king@canonical.com> <878tnph8dy.fsf@linux.intel.com> Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org From: Colin Ian King Message-ID: Date: Tue, 28 Mar 2017 13:52:14 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <878tnph8dy.fsf@linux.intel.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28/03/17 13:51, Felipe Balbi wrote: > > Hi, > > Colin King writes: >> From: Colin Ian King >> >> Writing to td->next should be avoided after td has been freed using >> dma_pool_free. The intent was to nullify the next pointer, but this >> is potentially dangerous once it is back in the pool. Remove it. >> >> Detected by CoverityScan, CID#1091173 ("Write tp pointer after free") >> >> Signed-off-by: Colin Ian King >> --- >> drivers/usb/gadget/udc/pch_udc.c | 1 - >> 1 file changed, 1 deletion(-) >> >> diff --git a/drivers/usb/gadget/udc/pch_udc.c b/drivers/usb/gadget/udc/pch_udc.c >> index 84dcbcd756f0..08bbe2c24134 100644 >> --- a/drivers/usb/gadget/udc/pch_udc.c >> +++ b/drivers/usb/gadget/udc/pch_udc.c >> @@ -1523,7 +1523,6 @@ static void pch_udc_free_dma_chain(struct pch_udc_dev *dev, >> td = phys_to_virt(addr); >> addr2 = (dma_addr_t)td->next; >> dma_pool_free(dev->data_requests, td, addr); >> - td->next = 0x00; > > I already have a patch for this, thanks Ah, I somehow overlooked that. Good to see it is fixed. Colin > > 1f459262b0e1649a1e5ad12fa4c66eb76c2220ce > Author: Gustavo A. R. Silva > AuthorDate: Fri Mar 10 15:39:32 2017 -0600 > Commit: Felipe Balbi > CommitDate: Wed Mar 22 11:21:10 2017 +0200 > > usb: gadget: udc: remove pointer dereference after free > > Remove pointer dereference after free. > > Addresses-Coverity-ID: 1091173 > Acked-by: Michal Nazarewicz > Signed-off-by: Gustavo A. R. Silva > Signed-off-by: Felipe Balbi > > 1 file changed, 1 deletion(-) > drivers/usb/gadget/udc/pch_udc.c | 1 - > > modified drivers/usb/gadget/udc/pch_udc.c > @@ -1523,7 +1523,6 @@ static void pch_udc_free_dma_chain(struct pch_udc_dev *dev, > td = phys_to_virt(addr); > addr2 = (dma_addr_t)td->next; > pci_pool_free(dev->data_requests, td, addr); > - td->next = 0x00; > addr = addr2; > } > req->chain_len = 1; >