linux-kernel - [PATCH v1 1/1] PCI: Avoid potential out-of-bounds read in pci_dev_for_each

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Date:   Mon, 30 Oct 2023 13:42:18 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Jonas Gorski <jonas.gorski@...il.com>
Subject: [PATCH v1 1/1] PCI: Avoid potential out-of-bounds read in pci_dev_for_each_resource()

Coverity complains that pointer in the pci_dev_for_each_resource()
may be wrong, i.e. mighe be used for the out-of-bounds read.

There is no actual issue right now, because we have another check
afterwards and the out-of-bounds read is not being performed. In any
case it's better code with this get fixed, hence the proposed change.

As Jonas pointed out "It probably makes the code slightly less
performant as res will now be checked for being not NULL (which will
always be true), but I doubt it will be significant (or in any hot
paths)."

Fixes: 09cc90063240 ("PCI: Introduce pci_dev_for_each_resource()")
Reported-by: Bjorn Helgaas <helgaas@...nel.org>
Closes: https://lore.kernel.org/r/20230509182122.GA1259567@bhelgaas
Suggested-by: Jonas Gorski <jonas.gorski@...il.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 include/linux/pci.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 60ca768bc867..19adad23a204 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2127,14 +2127,14 @@ int pci_iobar_pfn(struct pci_dev *pdev, int bar, struct vm_area_struct *vma);
 	(pci_resource_end((dev), (bar)) ? 				\
 	 resource_size(pci_resource_n((dev), (bar))) : 0)
 
-#define __pci_dev_for_each_res0(dev, res, ...)				\
-	for (unsigned int __b = 0;					\
-	     res = pci_resource_n(dev, __b), __b < PCI_NUM_RESOURCES;	\
+#define __pci_dev_for_each_res0(dev, res, ...)					\
+	for (unsigned int __b = 0;						\
+	     __b < PCI_NUM_RESOURCES && (res = pci_resource_n(dev, __b));	\
 	     __b++)
 
-#define __pci_dev_for_each_res1(dev, res, __b)				\
-	for (__b = 0;							\
-	     res = pci_resource_n(dev, __b), __b < PCI_NUM_RESOURCES;	\
+#define __pci_dev_for_each_res1(dev, res, __b)					\
+	for (__b = 0;								\
+	     __b < PCI_NUM_RESOURCES && (res = pci_resource_n(dev, __b));	\
 	     __b++)
 
 #define pci_dev_for_each_resource(dev, res, ...)			\
-- 
2.40.0.1.gaa8946217a0b