Re: Driver core: warn when userspace writes to the uevent file in a non-supported way

Re: Driver core: warn when userspace writes to the uevent file in a non-supported way

[Alan Cox]

>     In the future we will allow the uevent type to be written to the uevent
>     file to trigger the different types of uevents.  But for now, as we only
>     support the ADD event, warn if userspace tries to write anything else to
>     this file.
>     
>     Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
>     Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
> ---
>  drivers/base/core.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 72c6ee5..f69305c 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -296,6 +296,9 @@ out:
>  static ssize_t store_uevent(struct device *dev, struct device_attribute *attr,
>  			    const char *buf, size_t count)
>  {
> +	if (memcmp(buf, "add", 3) != 0)
> +		dev_err(dev, "uevent: unsupported action-string; this will "
> +			"be ignored in a future kernel version");

Warnings good, lack of rate limiting extremely bad indeed.

Re: Driver core: warn when userspace writes to the uevent file in a non-supported way

[Alan Cox]

> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -296,6 +296,9 @@ out:
>  static ssize_t store_uevent(struct device *dev, struct device_attribute *attr,
>  			    const char *buf, size_t count)
>  {
> +	if (memcmp(buf, "add", 3) != 0)
> +		dev_err(dev, "uevent: unsupported action-string; this will "
> +			"be ignored in a future kernel version");
>  	kobject_uevent(&dev->kobj, KOBJ_ADD);
>  	return count;
>  }


And checking for "add" without actually checking if count >= 3 is very
ugly style indeed. Not afaict any kind of security risk as the next 3
bytes are always going to be readable