[PATCH libftnl 04/12] src: expr: make sure NFTA_EXPR_NAME was parsed successfuly

[Florian Westphal <fw@strlen.de>]

LLM finding. Not a bug atm, the kernel always includes this.
While at it, upgrade to NUL_STRING.  Kernel always sets a trailing
NUL even for NLA_STRING, so we can enforce this.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 src/expr.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/expr.c b/src/expr.c
index 6462119e3eb2..980b317ff6db 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -251,7 +251,7 @@ static int nftnl_rule_parse_expr_cb(const struct nlattr *attr, void *data)
 
 	switch (type) {
 	case NFTA_EXPR_NAME:
-		if (mnl_attr_validate(attr, MNL_TYPE_STRING) < 0)
+		if (mnl_attr_validate(attr, MNL_TYPE_NUL_STRING) < 0)
 			abi_breakage();
 		break;
 	case NFTA_EXPR_DATA:
@@ -272,6 +272,9 @@ struct nftnl_expr *nftnl_expr_parse(struct nlattr *attr)
 	if (mnl_attr_parse_nested(attr, nftnl_rule_parse_expr_cb, tb) < 0)
 		goto err1;
 
+	if (!tb[NFTA_EXPR_NAME])
+		goto err1;
+
 	expr = nftnl_expr_alloc(mnl_attr_get_str(tb[NFTA_EXPR_NAME]));
 	if (expr == NULL)
 		goto err1;
-- 
2.55.0