From: Breno Leitao <leitao@debian.org>
Date: Mon, 14 Apr 2025 13:24:10 +0000 (-0700)
Subject: rtnetlink: Use nlmsg_payload in valid_fdb_dump_strict
X-Git-Tag: v6.16-rc1~132^2~297^2~6
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=77d02290366f058dce2555468a48ed8d62d95939;p=thirdparty%2Fkernel%2Fstable.git

rtnetlink: Use nlmsg_payload in valid_fdb_dump_strict

Leverage the new nlmsg_payload() helper to avoid checking for message
size and then reading the nlmsg data.

Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250414-nlmsg-v2-4-3d90cb42c6af@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 38526210b8fdd..f5c018090efc3 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -4887,12 +4887,12 @@ static int valid_fdb_dump_strict(const struct nlmsghdr *nlh,
 	struct ndmsg *ndm;
 	int err, i;
 
-	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ndm))) {
+	ndm = nlmsg_payload(nlh, sizeof(*ndm));
+	if (!ndm) {
 		NL_SET_ERR_MSG(extack, "Invalid header for fdb dump request");
 		return -EINVAL;
 	}
 
-	ndm = nlmsg_data(nlh);
 	if (ndm->ndm_pad1  || ndm->ndm_pad2  || ndm->ndm_state ||
 	    ndm->ndm_flags || ndm->ndm_type) {
 		NL_SET_ERR_MSG(extack, "Invalid values in header for fdb dump request");