4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Nicolai Stange <nsta...@suse.de>

commit bf563b01c2895a4bfd1a29cc5abc67fe706ecffd upstream.

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.

Reject driver_override values of these lengths in driver_override_store().

This is in close analogy to commit 4efe874aace5 ("PCI: Don't read past the
end of sysfs "driver_override" buffer") from Sasha Levin.

Fixes: 3d713e0e382e ("driver core: platform: add device binding path 
'driver_override'")
Signed-off-by: Nicolai Stange <nsta...@suse.de>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/base/platform.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -809,7 +809,8 @@ static ssize_t driver_override_store(str
        struct platform_device *pdev = to_platform_device(dev);
        char *driver_override, *old, *cp;
 
-       if (count > PATH_MAX)
+       /* We need to keep extra room for a newline */
+       if (count >= (PAGE_SIZE - 1))
                return -EINVAL;
 
        driver_override = kstrndup(buf, count, GFP_KERNEL);


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