From: Florian Westphal <fw@strlen.de>
Date: Thu, 8 May 2025 14:29:04 +0000 (+0200)
Subject: src: netlink: fix crash when ops doesn't support udata
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=be737a1986bfee0ddea4bee7863dca0123a2bcbc;p=thirdparty%2Fnftables.git

src: netlink: fix crash when ops doesn't support udata

Whenever a new version adds udata support to an expression, then old
versions of nft will crash when trying to list such a ruleset generated
by a more recent version of nftables.

Fix this by falling back to 'type' format.

Fixes: 6e48df5329ea ('src: add "typeof" build/parse/print support')
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Pablo Neira Ayuso <pablo@netfilter.org>
---

diff --git a/src/netlink.c b/src/netlink.c
index 86ca3214..d8891245 100644
--- a/src/netlink.c
+++ b/src/netlink.c
@@ -937,7 +937,7 @@ static struct expr *set_make_key(const struct nftnl_udata *attr)
 
 	etype = nftnl_udata_get_u32(ud[NFTNL_UDATA_SET_TYPEOF_EXPR]);
 	ops = expr_ops_by_type_u32(etype);
-	if (!ops)
+	if (!ops || !ops->parse_udata)
 		return NULL;
 
 	expr = ops->parse_udata(ud[NFTNL_UDATA_SET_TYPEOF_DATA]);