intervals: BUG on prefix expressions without value

commit 49721e28db3e7b28f443bf963547c12f4dcf856d upstream.

Its possible to end up with prefix expressions that have
a symbolic expression, e.g.:

table t {
        set s {
                type inet_service
                flags interval
                elements = { 172.16.0.0/16 }
        }

        set s {
                type inet_service
                flags interval
                elements = { 0-1024, 8080-8082, 10000-40000 }
        }
}

Without this change, nft will crash.  We end up in setelem_expr_to_range()
with prefix "/16" for the symbolic expression "172.16.0.0".

We than pass invalid mpz_t pointer into libgmp.

This isn't a real fix, but instead of blindly assuming that the attached
expression has a gmp value die with at least some info.

Signed-off-by: Florian Westphal <fw@strlen.de>

diff --git a/src/intervals.c b/src/intervals.c
index d79c52c58710a77a53a920648ef2d1c6fb0ba26d..af48d5ec1ac0f70a0ffb931a1d2ccd3385867057 100644 (file)
--- a/src/intervals.c
+++ b/src/intervals.c
@@ -24,6 +24,9 @@ static void setelem_expr_to_range(struct expr *expr)
        case EXPR_RANGE:
                break;
        case EXPR_PREFIX:
+               if (expr->key->prefix->etype != EXPR_VALUE)
+                       BUG("Prefix for unexpected type %d", expr->key->prefix->etype);
+
                mpz_init(rop);
                mpz_bitmask(rop, expr->key->len - expr->key->prefix_len);
                if (expr_basetype(expr)->type == TYPE_STRING)