linux-kernel - [PATCH] net: fix NULL ptr dereference in nl802154_del_llsec

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Date:   Sat,  3 Apr 2021 18:18:51 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     alex.aring@...il.com, stefan@...enfreihafen.org,
        davem@...emloft.net
Cc:     linux-wpan@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Pavel Skripkin <paskripkin@...il.com>,
        syzbot+ac5c11d2959a8b3c4806@...kaller.appspotmail.com
Subject: [PATCH] net: fix NULL ptr dereference in nl802154_del_llsec_key

syzbot reported NULL ptr dereference in nl802154_del_llsec_key()[1]
The problem was in case of info->attrs[NL802154_ATTR_SEC_KEY] == NULL.
nla_parse_nested_deprecated()[2] doesn't check this condition before calling
nla_len()[3]

Call Trace:
 nla_len include/net/netlink.h:1148 [inline]                       [3]
 nla_parse_nested_deprecated include/net/netlink.h:1231 [inline]   [2]
 nl802154_del_llsec_key+0x16d/0x320 net/ieee802154/nl802154.c:1595 [1]
 genl_family_rcv_msg_doit+0x228/0x320 net/netlink/genetlink.c:739
 genl_family_rcv_msg net/netlink/genetlink.c:783 [inline]
 genl_rcv_msg+0x328/0x580 net/netlink/genetlink.c:800

Reported-by: syzbot+ac5c11d2959a8b3c4806@...kaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
---
 net/ieee802154/nl802154.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ieee802154/nl802154.c b/net/ieee802154/nl802154.c
index 7c5a1aa5adb4..2f0a138bd5eb 100644
--- a/net/ieee802154/nl802154.c
+++ b/net/ieee802154/nl802154.c
@@ -1592,7 +1592,8 @@ static int nl802154_del_llsec_key(struct sk_buff *skb, struct genl_info *info)
 	struct nlattr *attrs[NL802154_KEY_ATTR_MAX + 1];
 	struct ieee802154_llsec_key_id id;
 
-	if (nla_parse_nested_deprecated(attrs, NL802154_KEY_ATTR_MAX, info->attrs[NL802154_ATTR_SEC_KEY], nl802154_key_policy, info->extack))
+	if (!info->attrs[NL802154_ATTR_SEC_KEY] ||
+	    nla_parse_nested_deprecated(attrs, NL802154_KEY_ATTR_MAX, info->attrs[NL802154_ATTR_SEC_KEY], nl802154_key_policy, info->extack))
 		return -EINVAL;
 
 	if (ieee802154_llsec_parse_key_id(attrs[NL802154_KEY_ATTR_ID], &id) < 0)
-- 
2.30.2