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

[Stephen Smalley]

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()?