Re: [PATCH] security: keys: Use kvfree_sensitive in a few places

[Alex Dewar]

On 2020-09-11 17:05, Denis Efremov wrote:
> Hi,
>
> same patch
>
> https://lkml.org/lkml/2020/8/27/168
>
> Thanks,
> Denis
Ah ok. Sorry for the noise!
> On 9/11/20 2:44 PM, Alex Dewar wrote:
> > In big_key.c, there are a few places where memzero_explicit + kvfree is
> > used. It is better to use kvfree_sensitive instead, which is more
> > readable and also prevents the compiler from eliding the call to
> > memzero_explicit. Fix this.
> >
> > Signed-off-by: Alex Dewar <alex.dewar90@xxxxxxxxx>
> > ---
> >   security/keys/big_key.c | 9 +++------
> >   1 file changed, 3 insertions(+), 6 deletions(-)
> >
> > diff --git a/security/keys/big_key.c b/security/keys/big_key.c
> > index 691347dea3c1..d17e5f09eeb8 100644
> > --- a/security/keys/big_key.c
> > +++ b/security/keys/big_key.c
> > @@ -121,8 +121,7 @@ int big_key_preparse(struct key_preparsed_payload *prep)
> >   		*path = file->f_path;
> >   		path_get(path);
> >   		fput(file);
> > -		memzero_explicit(buf, enclen);
> > -		kvfree(buf);
> > +		kvfree_sensitive(buf, enclen);
> >   	} else {
> >   		/* Just store the data in a buffer */
> >   		void *data = kmalloc(datalen, GFP_KERNEL);
> > @@ -140,8 +139,7 @@ int big_key_preparse(struct key_preparsed_payload *prep)
> >   err_enckey:
> >   	kfree_sensitive(enckey);
> >   error:
> > -	memzero_explicit(buf, enclen);
> > -	kvfree(buf);
> > +	kvfree_sensitive(buf, enclen);
> >   	return ret;
> >   }
> >   
> > @@ -273,8 +271,7 @@ long big_key_read(const struct key *key, char *buffer, size_t buflen)
> >   err_fput:
> >   		fput(file);
> >   error:
> > -		memzero_explicit(buf, enclen);
> > -		kvfree(buf);
> > +		kvfree_sensitive(buf, enclen);
> >   	} else {
> >   		ret = datalen;
> >   		memcpy(buffer, key->payload.data[big_key_data], datalen);