On Fri, Jun 07, 2019 at 10:39:05AM +0200, Ondrej Mosnacek wrote:
> On Thu, Jun 6, 2019 at 11:23 AM Gen Zhang <blackgod016574@xxxxxxxxx> wrote:
> > In selinux_add_mnt_opt(), 'val' is allocated by kmemdup_nul(). It returns
> > NULL when fails. So 'val' should be checked. And 'mnt_opts' should be
> > freed when error.
> >
> > Signed-off-by: Gen Zhang <blackgod016574@xxxxxxxxx>
> > Fixes: 757cbe597fe8 ("LSM: new method: ->sb_add_mnt_opt()")
> > ---
> > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> > index 3ec702c..4e4c1c6 100644
> > --- a/security/selinux/hooks.c
> > +++ b/security/selinux/hooks.c
> > @@ -1052,15 +1052,23 @@ 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) {
> > + rc = -ENOMEM;
> > + goto free_opt;
> > + }
> > + }
> > rc = selinux_add_opt(token, val, mnt_opts);
> > if (unlikely(rc)) {
> > kfree(val);
> > - if (*mnt_opts) {
> > - selinux_free_mnt_opts(*mnt_opts);
> > - *mnt_opts = NULL;
> > - }
> > + goto free_opt;
> > + }
> > + return rc;
>
> At this point rc is guaranteed to be 0, so you can just 'return 0' for
> clarity. Also, I visually prefer an empty line between a return
> statement and a goto label, but I'm not sure what is the
> general/maintainer's preference.
Am I supposed to revise and send a patch v4 for this, or let the
maintainer do this? :-)
Thanks
Gen
>
> Also, you should drop the "lsm: " from the subject - it is redundant
> and doesn't follow the SELinux convention. See `git log --oneline --
> security/selinux/` for what the subjects usually look like - mostly we
> just go with "selinux: <description>" (or "LSM: <description>" when
> the changes affect the shared LSM interface).
Thanks for your comments.
>
> > +free_opt:
> > + if (*mnt_opts) {
> > + selinux_free_mnt_opts(*mnt_opts);
> > + *mnt_opts = NULL;
> > }
> > return rc;
> > }
>
> --
> Ondrej Mosnacek <omosnace at redhat dot com>
> Software Engineer, Security Technologies
> Red Hat, Inc.
