From: Greg Kroah-Hartman gregkh@linuxfoundation.org
commit 5666a274a6d54372d6b79b1f78682a9d827e679e upstream.
Python likes to send an empty string for some sysfs files, including the driver_override field. When commit 23d99baf9d72 ("PCI: Use driver_set_override() instead of open-coding") moved the PCI core to use the driver core function instead of hand-rolling their own handler, this showed up as a regression from some userspace tools, like DPDK.
Fix this up by actually looking at the length of the string first instead of trusting that userspace got it correct.
Fixes: 23d99baf9d72 ("PCI: Use driver_set_override() instead of open-coding") Cc: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org Cc: Bjorn Helgaas bhelgaas@google.com Cc: "Rafael J. Wysocki" rafael@kernel.org Cc: Andy Shevchenko andy.shevchenko@gmail.com Cc: stable stable@kernel.org Reported-by: Stephen Hemminger stephen@networkplumber.org Tested-by: Huisong Li lihuisong@huawei.com Reviewed-by: Stephen Hemminger stephen@networkplumber.org Reviewed-by: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org Link: https://lore.kernel.org/r/20220901163734.3583106-1-gregkh@linuxfoundation.or... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/base/driver.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/drivers/base/driver.c +++ b/drivers/base/driver.c @@ -63,6 +63,12 @@ int driver_set_override(struct device *d if (len >= (PAGE_SIZE - 1)) return -EINVAL;
+ /* + * Compute the real length of the string in case userspace sends us a + * bunch of \0 characters like python likes to do. + */ + len = strlen(s); + if (!len) { /* Empty string passed - clear override */ device_lock(dev);