2022-09-01 17:48:42

by Greg Kroah-Hartman

Subject: [PATCH] driver core: fix driver_set_override() issue with empty strings

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.

Reported-by: Stephen Hemminger <[email protected]>
Fixes: 23d99baf9d72 ("PCI: Use driver_set_override() instead of open-coding")
Cc: Krzysztof Kozlowski <[email protected]>
Cc: Bjorn Helgaas <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: stable <[email protected]>
Tested-by: Huisong Li <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/base/driver.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/drivers/base/driver.c b/drivers/base/driver.c
index 15a75afe6b84..676b6275d5b5 100644
--- a/drivers/base/driver.c
+++ b/drivers/base/driver.c
@@ -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);
--
2.37.3

2022-09-01 18:02:01

by Stephen Hemminger

Subject: Re: [PATCH] driver core: fix driver_set_override() issue with empty strings

On Thu, 1 Sep 2022 18:37:34 +0200
Greg Kroah-Hartman <[email protected]> wrote:

> 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.
>
> Reported-by: Stephen Hemminger <[email protected]>
> Fixes: 23d99baf9d72 ("PCI: Use driver_set_override() instead of open-coding")
> Cc: Krzysztof Kozlowski <[email protected]>
> Cc: Bjorn Helgaas <[email protected]>
> Cc: "Rafael J. Wysocki" <[email protected]>
> Cc: Andy Shevchenko <[email protected]>
> Cc: stable <[email protected]>
> Tested-by: Huisong Li <[email protected]>
> Signed-off-by: Greg Kroah-Hartman <[email protected]>
> ---
> drivers/base/driver.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/base/driver.c b/drivers/base/driver.c
> index 15a75afe6b84..676b6275d5b5 100644
> --- a/drivers/base/driver.c
> +++ b/drivers/base/driver.c
> @@ -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);

Thanks for addressing this.

Reviewed-by: Stephen Hemminger <[email protected]>

2022-09-05 06:47:47

by Krzysztof Kozlowski

Subject: Re: [PATCH] driver core: fix driver_set_override() issue with empty strings

On 01/09/2022 19:37, Greg Kroah-Hartman wrote:
> 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.
>
> Reported-by: Stephen Hemminger <[email protected]>
> Fixes: 23d99baf9d72 ("PCI: Use driver_set_override() instead of open-coding")
> Cc: Krzysztof Kozlowski <[email protected]>
> Cc: Bjorn Helgaas <[email protected]>
> Cc: "Rafael J. Wysocki" <[email protected]>
> Cc: Andy Shevchenko <[email protected]>
> Cc: stable <[email protected]>
> Tested-by: Huisong Li <[email protected]>


Reviewed-by: Krzysztof Kozlowski <[email protected]>


Best regards,
Krzysztof