From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: [RFC 2/5] bus/pci: fix TOCTOU issue Date: Tue, 6 Nov 2018 13:48:58 -0800 Message-ID: <20181106214901.1392-3-stephen@networkplumber.org> References: <20181106214901.1392-1-stephen@networkplumber.org> Cc: Stephen Hemminger To: dev@dpdk.org Return-path: Received: from mail-pg1-f194.google.com (mail-pg1-f194.google.com [209.85.215.194]) by dpdk.org (Postfix) with ESMTP id 1F6DB2D13 for ; Tue, 6 Nov 2018 22:49:07 +0100 (CET) Received: by mail-pg1-f194.google.com with SMTP id w7so6383635pgp.13 for ; Tue, 06 Nov 2018 13:49:07 -0800 (PST) In-Reply-To: <20181106214901.1392-1-stephen@networkplumber.org> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Using access followed by open causes a static analysis warning about Time of check versus Time of use. Also, access() and open() have different UID permission checks. This is not a serious problem; but easy to fix by using errno instead. Coverity issue: 300870 Fixes: 4a928ef9f611 ("bus/pci: enable write combining during mapping") Signed-off-by: Stephen Hemminger --- drivers/bus/pci/linux/pci_uio.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/drivers/bus/pci/linux/pci_uio.c b/drivers/bus/pci/linux/pci_uio.c index 112ac51dddcc..8521fe63b0ae 100644 --- a/drivers/bus/pci/linux/pci_uio.c +++ b/drivers/bus/pci/linux/pci_uio.c @@ -306,12 +306,11 @@ pci_uio_map_resource_by_index(struct rte_pci_device *dev, int res_idx, loc->domain, loc->bus, loc->devid, loc->function, res_idx); - if (access(devname, R_OK|W_OK) != -1) { - fd = open(devname, O_RDWR); - if (fd < 0) - RTE_LOG(INFO, EAL, "%s cannot be mapped. " - "Fall-back to non prefetchable mode.\n", - devname); + fd = open(devname, O_RDWR); + if (fd < 0 && errno != ENOENT) { + RTE_LOG(INFO, EAL, "%s cannot be mapped. " + "Fall-back to non prefetchable mode.\n", + devname); } } -- 2.17.1