From 8f54619deab26614e850adbf8a60d33f7c5b4736 Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Tue, 2 Apr 2019 11:51:05 -0700 Subject: [PATCH] bus/pci: fix TOCTOU for sysfs access [ upstream commit c530aa78e3747cdd273310eeb9c50603da7f9cb6 ] 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 Reviewed-by: David Marchand --- 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 09ecbb7aad..0d1b9aa347 100644 --- a/drivers/bus/pci/linux/pci_uio.c +++ b/drivers/bus/pci/linux/pci_uio.c @@ -314,12 +314,11 @@ 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); } }