[PATCH 4.9 36/47] net: ieee802154: fix nl802154 del llsec dev

[Greg Kroah-Hartman]

From: Alexander Aring <aahringo@xxxxxxxxxx>

commit 3d1eac2f45585690d942cf47fd7fbd04093ebd1b upstream.

This patch fixes a nullpointer dereference if NL802154_ATTR_SEC_DEVICE is
not set by the user. If this is the case nl802154 will return -EINVAL.

Reported-by: syzbot+d946223c2e751d136c94@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Alexander Aring <aahringo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210221174321.14210-2-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
@@ -1796,7 +1796,8 @@ static int nl802154_del_llsec_dev(struct
 	struct nlattr *attrs[NL802154_DEV_ATTR_MAX + 1];
 	__le64 extended_addr;
 
-	if (nla_parse_nested(attrs, NL802154_DEV_ATTR_MAX,
+	if (!info->attrs[NL802154_ATTR_SEC_DEVICE] ||
+	    nla_parse_nested(attrs, NL802154_DEV_ATTR_MAX,
 			     info->attrs[NL802154_ATTR_SEC_DEVICE],
 			     nl802154_dev_policy))
 		return -EINVAL;