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From: Stephen Hemminger <stephen@networkplumber.org>
To: ferruh.yigit@intel.com, bruce.richardson@intel.com,
	gaetan.rivet@6wind.com
Cc: dev@dpdk.org, Stephen Hemminger <stephen@networkplumber.org>
Subject: [dpdk-dev] [PATCH v2] bus/pci: fix TOCTOU issue
Date: Tue,  2 Apr 2019 11:51:05 -0700	[thread overview]
Message-ID: <20190402185105.2852-1-stephen@networkplumber.org> (raw)
Message-ID: <20190402185105.P5kcdGYGucgDJsCVFBjhMbXDaWFwXc-WEfMleJOxsbg@z> (raw)

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 <stephen@networkplumber.org>
---
v2 - add more CC to original mail, and rebase

 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 09ecbb7aad25..0d1b9aa347ba 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);
 		}
 	}
 
-- 
2.17.1


             reply	other threads:[~2019-04-02 18:51 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-02 18:51 Stephen Hemminger [this message]
2019-04-02 18:51 ` Stephen Hemminger
2019-06-14  7:16 ` David Marchand
2019-06-14  7:35   ` Thomas Monjalon

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