Re: [PATCH v4 20/19] LSM: Correct file blob free empty blob check

[Kees Cook]

On Wed, Sep 26, 2018 at 2:57 PM, Casey Schaufler <casey@xxxxxxxxxxxxxxxx> wrote:
> Instead of checking if the kmem_cache for file blobs
> has been initialized check if the blob is NULL. This
> allows non-blob using modules to do other kinds of
> clean up in the security_file_free hooks.
>
> Signed-off-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

This looks like it should get folded into "LSM: Infrastructure
management of the file security".

-Kees


> ---
>  security/security.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/security/security.c b/security/security.c
> index e7c8506041f1..76f7dc49b63c 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -1202,14 +1202,13 @@ void security_file_free(struct file *file)
>  {
>         void *blob;
>
> -       if (!lsm_file_cache)
> -               return;
> -
>         call_void_hook(file_free_security, file);
>
>         blob = file->f_security;
> -       file->f_security = NULL;
> -       kmem_cache_free(lsm_file_cache, blob);
> +       if (blob) {
> +               file->f_security = NULL;
> +               kmem_cache_free(lsm_file_cache, blob);
> +       }
>  }
>
>  int security_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> --
> 2.17.1
>
>



-- 
Kees Cook
Pixel Security