evaluate: fix double free on dtype release

We release ->dtype twice, will either segfault or assert
on dtype->refcount != 0 check in datatype_free().

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

diff --git a/src/evaluate.c b/src/evaluate.c
index 16ad6473db1ad4da180fc469f4ab6a742bb595b7..58cc811aca9a718361cdd1ab209bf9f80c0d5a58 100644 (file)
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -1171,7 +1171,7 @@ static int expr_evaluate_prefix(struct eval_ctx *ctx, struct expr **expr)
        base = prefix->prefix;
        assert(expr_is_constant(base));
 
-       prefix->dtype     = base->dtype;
+       prefix->dtype     = datatype_get(base->dtype);
        prefix->byteorder = base->byteorder;
        prefix->len       = base->len;
        prefix->flags    |= EXPR_F_CONSTANT;

diff --git a/tests/shell/testcases/bogons/nft-f/double-free-on-binop-dtype_assert b/tests/shell/testcases/bogons/nft-f/double-free-on-binop-dtype_assert
new file mode 100644 (file)
index 0000000..b7a9a1c
--- /dev/null
+++ b/tests/shell/testcases/bogons/nft-f/double-free-on-binop-dtype_assert
@@ -0,0 +1,6 @@
+table inet t {
+       chain c {
+               udp length . @th,160,118 vmap { 47-63 . 0xe3731353631303331313037353532/3 : accept }
+               jump noexist # only here so this fails to load after patch.
+       }
+}