[PATCH 4.9 35/47] net: ieee802154: fix nl802154 del llsec key

[Greg Kroah-Hartman]

From: Alexander Aring <aahringo@xxxxxxxxxx>

commit 37feaaf5ceb2245e474369312bb7b922ce7bce69 upstream.

This patch fixes a nullpointer dereference if NL802154_ATTR_SEC_KEY is
not set by the user. If this is the case nl802154 will return -EINVAL.

Reported-by: syzbot+ac5c11d2959a8b3c4806@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Alexander Aring <aahringo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210221174321.14210-1-aahringo@xxxxxxxxxx
Signed-off-by: Stefan Schmidt <stefan@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/ieee802154/nl802154.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/ieee802154/nl802154.c
+++ b/net/ieee802154/nl802154.c
@@ -1627,7 +1627,8 @@ static int nl802154_del_llsec_key(struct
 	struct nlattr *attrs[NL802154_KEY_ATTR_MAX + 1];
 	struct ieee802154_llsec_key_id id;
 
-	if (nla_parse_nested(attrs, NL802154_KEY_ATTR_MAX,
+	if (!info->attrs[NL802154_ATTR_SEC_KEY] ||
+	    nla_parse_nested(attrs, NL802154_KEY_ATTR_MAX,
 			     info->attrs[NL802154_ATTR_SEC_KEY],
 			     nl802154_key_policy))
 		return -EINVAL;