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driver core: fix driver_set_override() issue with empty strings

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Python likes to send an empty string for some sysfs files, including the
driver_override field.  When commit 23d99baf9d ("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: 23d99baf9d ("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.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Greg Kroah-Hartman 2022-09-01 18:37:34 +02:00
parent c749b27505
commit 5666a274a6
1 changed files with 6 additions and 0 deletions
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6
drivers/base/driver.c
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@ -63,6 +63,12 @@ int driver_set_override(struct device *dev, const char **override,
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);