[PATCH 5.6 101/166] macsec: fix NULL dereference in macsec_upd_offload()

[Greg Kroah-Hartman]

From: Davide Caratti <dcaratti@xxxxxxxxxx>

[ Upstream commit aa81700cf2326e288c9ca1fe7b544039617f1fc2 ]

macsec_upd_offload() gets the value of MACSEC_OFFLOAD_ATTR_TYPE
without checking its presence in the request message, and this causes
a NULL dereference. Fix it rejecting any configuration that does not
include this attribute.

Reported-and-tested-by: syzbot+7022ab7c383875c17eff@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: dcb780fb2795 ("net: macsec: add nla support for changing the offloading selection")
Signed-off-by: Davide Caratti <dcaratti@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/macsec.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c
index 061aada4748a7..9b4ae5c36da6b 100644
--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -2398,6 +2398,9 @@ static int macsec_upd_offload(struct sk_buff *skb, struct genl_info *info)
 		return PTR_ERR(dev);
 	macsec = macsec_priv(dev);
 
+	if (!tb_offload[MACSEC_OFFLOAD_ATTR_TYPE])
+		return -EINVAL;
+
 	offload = nla_get_u8(tb_offload[MACSEC_OFFLOAD_ATTR_TYPE]);
 	if (macsec->offload == offload)
 		return 0;
-- 
2.20.1