On Fri, May 31, 2019 at 11:55:23AM -0400, Paul Moore wrote:
> On Thu, May 30, 2019 at 4:55 AM Gen Zhang <blackgod016574@xxxxxxxxx> wrote:
> >
> > In selinux_add_mnt_opt(), 'val' is allcoted by kmemdup_nul(). It returns
> > NULL when fails. So 'val' should be checked.
> >
> > Signed-off-by: Gen Zhang <blackgod016574@xxxxxxxxx>
> > Fixes: 757cbe597fe8 ("LSM: new method: ->sb_add_mnt_opt()")
>
> Previous comments regarding "selinux:" instead of "hooks:" apply here as well.
>
Thanks for your comments, Paul. I will make some changes.
> > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> > index 3ec702c..4797c63 100644
> > --- a/security/selinux/hooks.c
> > +++ b/security/selinux/hooks.c
> > @@ -1052,8 +1052,11 @@ static int selinux_add_mnt_opt(const char *option, const char *val, int len,
> > if (token == Opt_error)
> > return -EINVAL;
> >
> > - if (token != Opt_seclabel)
> > - val = kmemdup_nul(val, len, GFP_KERNEL);
> > + if (token != Opt_seclabel) {
> > + val = kmemdup_nul(val, len, GFP_KERNEL);
> > + if (!val)
> > + return -ENOMEM;
>
> It looks like this code is only ever called by NFS, which will
> eventually clean up mnt_opts via security_free_mnt_opts(), but since
> the selinux_add_opt() error handler below cleans up mnt_opts it might
> be safer to do the same here in case this function is called multiple
> times to add multiple options.
>
> > + }
> > rc = selinux_add_opt(token, val, mnt_opts);
> > if (unlikely(rc)) {
> > kfree(val);
>
> --
> paul moore
> www.paul-moore.com
Thanks
Gen
