Re: [PATCH v2 3/4] ARM: amba: Don't read past the end of sysfs "driver_override" buffer

From: Todd Kjos
Date: Wed Apr 25 2018 - 11:57:05 EST


Reviewed-by: Todd Kjos <tkjos@xxxxxxxxxxx>

On Tue, Apr 10, 2018 at 6:21 AM, Geert Uytterhoeven
<geert+renesas@xxxxxxxxx> wrote:
> When printing the driver_override parameter when it is 4095 and 4094
> bytes long, the printing code would access invalid memory because we
> need count + 1 bytes for printing.
>
> Cfr. commits 4efe874aace57dba ("PCI: Don't read past the end of sysfs
> "driver_override" buffer") and bf563b01c2895a4b ("driver core: platform:
> Don't read past the end of "driver_override" buffer").
>
> Fixes: 3cf385713460eb2b ("ARM: 8256/1: driver coamba: add device binding path 'driver_override'")
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> ---
> drivers/amba/bus.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> index 36c5653ced5742b7..4a3ac31c07d0ee49 100644
> --- a/drivers/amba/bus.c
> +++ b/drivers/amba/bus.c
> @@ -84,7 +84,8 @@ static ssize_t driver_override_store(struct device *_dev,
> struct amba_device *dev = to_amba_device(_dev);
> char *driver_override, *old, *cp;
>
> - if (count > PATH_MAX)
> + /* We need to keep extra room for a newline */
> + if (count >= (PAGE_SIZE - 1))
> return -EINVAL;
>
> driver_override = kstrndup(buf, count, GFP_KERNEL);
> --
> 2.7.4
>