Re: [kernel-hardening] [PATCH 3/4] Make static usermode helper binaries constant

[Rich Felker <dalias@libc.org>]

On Wed, Dec 14, 2016 at 10:50:52AM -0800, Greg KH wrote:
> 
> There are a number of usermode helper binaries that are "hard coded" in
> the kernel today, so mark them as "const" to make it harder for someone
> to change where the variables point to.

You're not preventing change of where they point to, but rather
preventing modification of the pointed-to data through these
pointers...

> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  drivers/macintosh/windfarm_core.c          | 2 +-
>  drivers/net/hamradio/baycom_epp.c          | 2 +-
>  drivers/pnp/pnpbios/core.c                 | 5 +++--
>  drivers/staging/greybus/svc_watchdog.c     | 4 ++--
>  drivers/staging/rtl8192e/rtl8192e/rtl_dm.c | 6 +++---
>  fs/nfsd/nfs4layouts.c                      | 6 ++++--
>  security/keys/request_key.c                | 7 ++++---
>  7 files changed, 18 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/macintosh/windfarm_core.c b/drivers/macintosh/windfarm_core.c
> index 465d770ab0bb..1b317cbb73cf 100644
> --- a/drivers/macintosh/windfarm_core.c
> +++ b/drivers/macintosh/windfarm_core.c
> @@ -74,7 +74,7 @@ static inline void wf_notify(int event, void *param)
>  
>  static int wf_critical_overtemp(void)
>  {
> -	static char * critical_overtemp_path = "/sbin/critical_overtemp";
> +	static const char * critical_overtemp_path = "/sbin/critical_overtemp";

Should be static char *const critical_overtemp_path, or if you prefer
static const char *const critical_overtemp_path (since the pointed-to
data is not modifiable either). Likewise elsewhere.

Rich