Re: [PATCH] selinux: fix undefined return of cond_evaluate_expr

[Paul Moore]

On Wed, Jun 17, 2020 at 9:58 AM Stephen Smalley
<stephen.smalley.work@xxxxxxxxx> wrote:
> On Wed, Jun 17, 2020 at 8:40 AM <trix@xxxxxxxxxx> wrote:
> >
> > From: Tom Rix <trix@xxxxxxxxxx>
> >
> > clang static analysis reports an undefined return
> >
> > security/selinux/ss/conditional.c:79:2: warning: Undefined or garbage value returned to caller [core.uninitialized.UndefReturn]
> >         return s[0];
> >         ^~~~~~~~~~~
> >
> > static int cond_evaluate_expr( ...
> > {
> >         u32 i;
> >         int s[COND_EXPR_MAXDEPTH];
> >
> >         for (i = 0; i < expr->len; i++)
> >           ...
> >
> >         return s[0];
> >
> > When expr->len is 0, the loop which sets s[0] never runs.
> >
> > So return -1 if the loop never runs.
> >
> > Signed-off-by: Tom Rix <trix@xxxxxxxxxx>
>
> Acked-by: Stephen Smalley <stephen.smalley.work@xxxxxxxxx>
>
> clang didn't complain about the similar pattern in
> security/selinux/ss/services.c:constraint_expr_eval()?

Related question: I appreciate the work you are doing Tom, can you
share how far along you are testing the SELinux code with clang?  I
ask because it would be nice to roll all of these patches up into one
PR for Linus instead of sending multiple updates.

-- 
paul moore
www.paul-moore.com