[PATCH] selinux: fix undefined return of cond_evaluate_expr

[trix]

From: Tom Rix <t...@redhat.com>

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 <t...@redhat.com>
---
 security/selinux/ss/conditional.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/security/selinux/ss/conditional.c 
b/security/selinux/ss/conditional.c
index 450bc02f4cd2..0cc7cdd58465 100644
--- a/security/selinux/ss/conditional.c
+++ b/security/selinux/ss/conditional.c
@@ -27,6 +27,9 @@ static int cond_evaluate_expr(struct policydb *p, struct 
cond_expr *expr)
        int s[COND_EXPR_MAXDEPTH];
        int sp = -1;
 
+       if (expr->len == 0)
+               return -1;
+
        for (i = 0; i < expr->len; i++) {
                struct cond_expr_node *node = &expr->nodes[i];
 
-- 
2.18.1