Re: [PATCH 2/4] ARM: amba: Fix race condition with driver_override

[Geert Uytterhoeven]

Hi Todd,

On Fri, Mar 2, 2018 at 7:23 PM, Todd Kjos  wrote:
> +stable
>
> what is the status of this patch? We'd like to get it into the android
> common branches to fix possible double free.

Thanks for your interest!

So far this patch (and the 3 others in the series) haven't received any
comments. If someone sends a Acked-by or Reviewed-by, I can submit them
to RMK's patch system.

Thanks!

> On Fri, Jan 19, 2018 at 7:24 AM, Geert Uytterhoeven
>  wrote:
>> The driver_override implementation is susceptible to a race condition
>> when different threads are reading vs storing a different driver
>> override.  Add locking to avoid this race condition.
>>
>> Cfr. commits 6265539776a0810b ("driver core: platform: fix race
>> condition with driver_override") and 9561475db680f714 ("PCI: Fix race
>> condition with driver_override").
>>
>> Fixes: 3cf385713460eb2b ("ARM: 8256/1: driver coamba: add device binding 
>> path 'driver_override'")
>> Signed-off-by: Geert Uytterhoeven 

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

Re: [PATCH 2/4] ARM: amba: Fix race condition with driver_override

[Geert Uytterhoeven]

Hi Todd,

On Fri, Mar 2, 2018 at 7:23 PM, Todd Kjos  wrote:
> +stable
>
> what is the status of this patch? We'd like to get it into the android
> common branches to fix possible double free.

Thanks for your interest!

So far this patch (and the 3 others in the series) haven't received any
comments. If someone sends a Acked-by or Reviewed-by, I can submit them
to RMK's patch system.

Thanks!

> On Fri, Jan 19, 2018 at 7:24 AM, Geert Uytterhoeven
>  wrote:
>> The driver_override implementation is susceptible to a race condition
>> when different threads are reading vs storing a different driver
>> override.  Add locking to avoid this race condition.
>>
>> Cfr. commits 6265539776a0810b ("driver core: platform: fix race
>> condition with driver_override") and 9561475db680f714 ("PCI: Fix race
>> condition with driver_override").
>>
>> Fixes: 3cf385713460eb2b ("ARM: 8256/1: driver coamba: add device binding 
>> path 'driver_override'")
>> Signed-off-by: Geert Uytterhoeven 

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

Re: [PATCH 2/4] ARM: amba: Fix race condition with driver_override

[Todd Kjos]

+stable

what is the status of this patch? We'd like to get it into the android
common branches to fix possible double free.

On Fri, Jan 19, 2018 at 7:24 AM, Geert Uytterhoeven
 wrote:
> The driver_override implementation is susceptible to a race condition
> when different threads are reading vs storing a different driver
> override.  Add locking to avoid this race condition.
>
> Cfr. commits 6265539776a0810b ("driver core: platform: fix race
> condition with driver_override") and 9561475db680f714 ("PCI: Fix race
> condition with driver_override").
>
> Fixes: 3cf385713460eb2b ("ARM: 8256/1: driver coamba: add device binding path 
> 'driver_override'")
> Signed-off-by: Geert Uytterhoeven 
> ---
>  drivers/amba/bus.c | 11 +--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> index 6ffd778352e6d953..36c5653ced5742b7 100644
> --- a/drivers/amba/bus.c
> +++ b/drivers/amba/bus.c
> @@ -69,8 +69,12 @@ static ssize_t driver_override_show(struct device *_dev,
> struct device_attribute *attr, char *buf)
>  {
> struct amba_device *dev = to_amba_device(_dev);
> +   ssize_t len;
>
> -   return sprintf(buf, "%s\n", dev->driver_override);
> +   device_lock(_dev);
> +   len = sprintf(buf, "%s\n", dev->driver_override);
> +   device_unlock(_dev);
> +   return len;
>  }
>
>  static ssize_t driver_override_store(struct device *_dev,
> @@ -78,7 +82,7 @@ static ssize_t driver_override_store(struct device *_dev,
>  const char *buf, size_t count)
>  {
> struct amba_device *dev = to_amba_device(_dev);
> -   char *driver_override, *old = dev->driver_override, *cp;
> +   char *driver_override, *old, *cp;
>
> if (count > PATH_MAX)
> return -EINVAL;
> @@ -91,12 +95,15 @@ static ssize_t driver_override_store(struct device *_dev,
> if (cp)
> *cp = '\0';
>
> +   device_lock(_dev);
> +   old = dev->driver_override;
> if (strlen(driver_override)) {
> dev->driver_override = driver_override;
> } else {
>kfree(driver_override);
>dev->driver_override = NULL;
> }
> +   device_unlock(_dev);
>
> kfree(old);
>
> --
> 2.7.4
>

Re: [PATCH 2/4] ARM: amba: Fix race condition with driver_override

[Todd Kjos]

+stable

what is the status of this patch? We'd like to get it into the android
common branches to fix possible double free.

On Fri, Jan 19, 2018 at 7:24 AM, Geert Uytterhoeven
 wrote:
> The driver_override implementation is susceptible to a race condition
> when different threads are reading vs storing a different driver
> override.  Add locking to avoid this race condition.
>
> Cfr. commits 6265539776a0810b ("driver core: platform: fix race
> condition with driver_override") and 9561475db680f714 ("PCI: Fix race
> condition with driver_override").
>
> Fixes: 3cf385713460eb2b ("ARM: 8256/1: driver coamba: add device binding path 
> 'driver_override'")
> Signed-off-by: Geert Uytterhoeven 
> ---
>  drivers/amba/bus.c | 11 +--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> index 6ffd778352e6d953..36c5653ced5742b7 100644
> --- a/drivers/amba/bus.c
> +++ b/drivers/amba/bus.c
> @@ -69,8 +69,12 @@ static ssize_t driver_override_show(struct device *_dev,
> struct device_attribute *attr, char *buf)
>  {
> struct amba_device *dev = to_amba_device(_dev);
> +   ssize_t len;
>
> -   return sprintf(buf, "%s\n", dev->driver_override);
> +   device_lock(_dev);
> +   len = sprintf(buf, "%s\n", dev->driver_override);
> +   device_unlock(_dev);
> +   return len;
>  }
>
>  static ssize_t driver_override_store(struct device *_dev,
> @@ -78,7 +82,7 @@ static ssize_t driver_override_store(struct device *_dev,
>  const char *buf, size_t count)
>  {
> struct amba_device *dev = to_amba_device(_dev);
> -   char *driver_override, *old = dev->driver_override, *cp;
> +   char *driver_override, *old, *cp;
>
> if (count > PATH_MAX)
> return -EINVAL;
> @@ -91,12 +95,15 @@ static ssize_t driver_override_store(struct device *_dev,
> if (cp)
> *cp = '\0';
>
> +   device_lock(_dev);
> +   old = dev->driver_override;
> if (strlen(driver_override)) {
> dev->driver_override = driver_override;
> } else {
>kfree(driver_override);
>dev->driver_override = NULL;
> }
> +   device_unlock(_dev);
>
> kfree(old);
>
> --
> 2.7.4
>