[PATCH] ieee802154: nl-mac: validate device pointers before dereference

[PATCH] ieee802154: nl-mac: validate device pointers before dereference

[Kalpesh Solanki]

A virtual network device (such as a TUN interface) can have its link
type set to ARPHRD_IEEE802154 via ioctl(tun_fd, TUNSETLINK,
ARPHRD_IEEE802154). However, such devices do not have an IEEE 802.15.4
private context allocated (dev->ieee802154_ptr is NULL) and do not
register MAC operations (dev->ml_priv / ieee802154_mlme_ops(dev) is NULL).

When dumping security keys via IEEE802154_LLSEC_LIST_KEY,
ieee802154_llsec_dump_table() iterates through all net devices and
dereferences data.ops->llsec assuming that any ARPHRD_IEEE802154 device
has valid mlme ops. Because data.ops is NULL, this causes an immediate
null-pointer dereference / General Protection Fault:

  Oops: general protection fault, probably for non-canonical address
  KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]
  RIP: 0010:ieee802154_llsec_dump_table+0x204/0x5d0
  Call Trace:
   <TASK>
   genl_dumpit+0x125/0x230 net/netlink/genetlink.c:1026
   netlink_dump+0x53b/0xd00 net/netlink/af_netlink.c:2351
   __netlink_dump_start+0x6d6/0x990 net/netlink/af_netlink.c:2466

Similarly, ieee802154_dump_iface() and ieee802154_nl_get_dev() assume
that ARPHRD_IEEE802154 devices have valid dev->ieee802154_ptr and
ieee802154_mlme_ops(dev) pointers.

Fix this by ensuring dev->ieee802154_ptr and ieee802154_mlme_ops(dev)
are non-NULL before proceeding in ieee802154_nl_get_dev(),
ieee802154_dump_iface(), and ieee802154_llsec_dump_table().

Fixes: 3e9c156e2c21 ("ieee802154: add netlink interfaces for llsec")
Cc: stable@vger.kernel.org
Reported-by: syzbot+9ea34da5ca6100593c90@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=9ea34da5ca6100593c90
Tested-by: syzbot+9ea34da5ca6100593c90@syzkaller.appspotmail.com
Signed-off-by: Kalpesh Solanki <skalpesh942@gmail.com>
---
 net/ieee802154/nl-mac.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/ieee802154/nl-mac.c b/net/ieee802154/nl-mac.c
index 74ef0a310af..1acde5af4b5 100644
--- a/net/ieee802154/nl-mac.c
+++ b/net/ieee802154/nl-mac.c
@@ -162,7 +162,8 @@ static struct net_device *ieee802154_nl_get_dev(struct genl_info *info)
 	if (!dev)
 		return NULL;
 
-	if (dev->type != ARPHRD_IEEE802154) {
+	if (dev->type != ARPHRD_IEEE802154 || !dev->ieee802154_ptr ||
+	    !ieee802154_mlme_ops(dev)) {
 		dev_put(dev);
 		return NULL;
 	}
@@ -437,7 +438,8 @@ int ieee802154_dump_iface(struct sk_buff *skb, struct netlink_callback *cb)
 
 	idx = 0;
 	for_each_netdev(net, dev) {
-		if (idx < s_idx || dev->type != ARPHRD_IEEE802154)
+		if (idx < s_idx || dev->type != ARPHRD_IEEE802154 ||
+		    !dev->ieee802154_ptr || !ieee802154_mlme_ops(dev))
 			goto cont;
 
 		if (ieee802154_nl_fill_iface(skb, NETLINK_CB(cb->skb).portid,
@@ -771,7 +773,8 @@ ieee802154_llsec_dump_table(struct sk_buff *skb, struct netlink_callback *cb,
 	int rc;
 
 	for_each_netdev(net, dev) {
-		if (idx < first_dev || dev->type != ARPHRD_IEEE802154)
+		if (idx < first_dev || dev->type != ARPHRD_IEEE802154 ||
+		    !dev->ieee802154_ptr || !ieee802154_mlme_ops(dev))
 			goto skip;
 
 		data.ops = ieee802154_mlme_ops(dev);
--