[PATCH 5.15 41/69] macsec: fix NULL deref in macsec_add_rxsa

Greg Kroah-Hartman
2022-08-01T12:05:14Z

From: Sabrina Dubroca <sd@queasysnail.net>

[ Upstream commit f46040eeaf2e523a4096199fd93a11e794818009 ]

Commit 48ef50fa866a added a test on tb_sa[MACSEC_SA_ATTR_PN], but
nothing guarantees that it's not NULL at this point. The same code was
added to macsec_add_txsa, but there it's not a problem because
validate_add_txsa checks that the MACSEC_SA_ATTR_PN attribute is
present.

Note: it's not possible to reproduce with iproute, because iproute
doesn't allow creating an SA without specifying the PN.

Fixes: 48ef50fa866a ("macsec: Netlink support of XPN cipher suites (IEEE 802.1AEbw)")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=208315
Reported-by: Frantisek Sumsal <fsumsal@redhat.com>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/macsec.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c
index e53b40359fd1..f72d4380374d 100644
--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -1751,7 +1751,8 @@ static int macsec_add_rxsa(struct sk_buff *skb, struct genl_info *info)
}

pn_len = secy->xpn ? MACSEC_XPN_PN_LEN : MACSEC_DEFAULT_PN_LEN;
- if (nla_len(tb_sa[MACSEC_SA_ATTR_PN]) != pn_len) {
+ if (tb_sa[MACSEC_SA_ATTR_PN] &&
+ nla_len(tb_sa[MACSEC_SA_ATTR_PN]) != pn_len) {
pr_notice("macsec: nl: add_rxsa: bad pn length: %d != %d\n",
nla_len(tb_sa[MACSEC_SA_ATTR_PN]), pn_len);
rtnl_unlock();
--
2.35.1