When printing the driver_override parameter when it is 4095 and 4094 bytes
long the printing code would access invalid memory because we need count+1
bytes for printing.

Cc: <[email protected]> # v3.16+
Fixes: 782a985d ("PCI: Introduce new device binding path using 
pci_dev.driver_override")
Cc: Alex Williamson <[email protected]>
Cc: Bjorn Helgaas <[email protected]>
Cc: Konrad Rzeszutek Wilk <[email protected]>
Cc: Alexander Graf <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
---
 drivers/pci/pci-sysfs.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index aa012fb..17459ed 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -521,7 +521,8 @@ static ssize_t driver_override_store(struct device *dev,
        struct pci_dev *pdev = to_pci_dev(dev);
        char *driver_override, *old = pdev->driver_override, *cp;
 
-       if (count > PATH_MAX)
+       /* We need to keep extra room for a newline */
+       if (count >= (PATH_MAX - 1))
                return -EINVAL;
 
        driver_override = kstrndup(buf, count, GFP_KERNEL);
-- 
1.7.10.4

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