From: Sabrina Dubroca <sd@queasysnail.net>
Date: Fri, 23 Sep 2022 11:07:09 +0200
Subject: macsec: don't free NULL metadata_dst
Patch-mainline: v6.1-rc1
Git-commit: c52add61c27ea23501be82a34854edd98e10e061
References: jsc#PED-1549

Commit 0a28bfd4971f added a metadata_dst to each tx_sc, but that's
only allocated when macsec_add_dev has run, which happens after device
registration. If the requested or computed SCI already exists, or if
linking to the lower device fails, we will panic because
metadata_dst_free can't handle NULL.

Reproducer:
    ip link add link $lower type macsec
    ip link add link $lower type macsec

Fixes: 0a28bfd4971f ("net/macsec: Add MACsec skb_metadata_dst Tx Data path support")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: Raed Salem <raeds@nvidia.com>
Link: https://lore.kernel.org/r/60f2a1965fe553e2cade9472407d0fafff8de8ce.1663923580.git.sd@queasysnail.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/macsec.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -3719,7 +3719,8 @@ static void macsec_free_netdev(struct ne
 {
 	struct macsec_dev *macsec = macsec_priv(dev);
 
-	metadata_dst_free(macsec->secy.tx_sc.md_dst);
+	if (macsec->secy.tx_sc.md_dst)
+		metadata_dst_free(macsec->secy.tx_sc.md_dst);
 	free_percpu(macsec->stats);
 	free_percpu(macsec->secy.tx_sc.stats);