[net] ieee802154: 6lowpan: fix possible NULL deref in lowpan_device_event()

Message ID 1520268663.109662.5.camel@gmail.com
State Accepted
Delegated to: David Miller
Headers show
Series
  • [net] ieee802154: 6lowpan: fix possible NULL deref in lowpan_device_event()
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Commit Message

Eric Dumazet March 5, 2018, 4:51 p.m.
From: Eric Dumazet <edumazet@google.com>

A tun device type can trivially be set to arbitrary value using
TUNSETLINK ioctl().

Therefore, lowpan_device_event() must really check that ieee802154_ptr
is not NULL.

Fixes: 2c88b5283f60d ("ieee802154: 6lowpan: remove check on null")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Alexander Aring <alex.aring@gmail.com>
Cc: Stefan Schmidt <stefan@osg.samsung.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
---
 net/ieee802154/6lowpan/core.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

Comments

David Miller March 5, 2018, 5 p.m. | #1
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Mon, 05 Mar 2018 08:51:03 -0800

> From: Eric Dumazet <edumazet@google.com>
> 
> A tun device type can trivially be set to arbitrary value using
> TUNSETLINK ioctl().
> 
> Therefore, lowpan_device_event() must really check that ieee802154_ptr
> is not NULL.
> 
> Fixes: 2c88b5283f60d ("ieee802154: 6lowpan: remove check on null")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Alexander Aring <alex.aring@gmail.com>
> Cc: Stefan Schmidt <stefan@osg.samsung.com>
> Reported-by: syzbot <syzkaller@googlegroups.com>

Adding linux-wpan list.

> ---
>  net/ieee802154/6lowpan/core.c |   12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/net/ieee802154/6lowpan/core.c b/net/ieee802154/6lowpan/core.c
> index 974765b7d92a..e9f0489e4229 100644
> --- a/net/ieee802154/6lowpan/core.c
> +++ b/net/ieee802154/6lowpan/core.c
> @@ -206,9 +206,13 @@ static inline void lowpan_netlink_fini(void)
>  static int lowpan_device_event(struct notifier_block *unused,
>  			       unsigned long event, void *ptr)
>  {
> -	struct net_device *wdev = netdev_notifier_info_to_dev(ptr);
> +	struct net_device *ndev = netdev_notifier_info_to_dev(ptr);
> +	struct wpan_dev *wpan_dev;
>  
> -	if (wdev->type != ARPHRD_IEEE802154)
> +	if (ndev->type != ARPHRD_IEEE802154)
> +		return NOTIFY_DONE;
> +	wpan_dev = ndev->ieee802154_ptr;
> +	if (!wpan_dev)
>  		return NOTIFY_DONE;
>  
>  	switch (event) {
> @@ -217,8 +221,8 @@ static int lowpan_device_event(struct notifier_block *unused,
>  		 * also delete possible lowpan interfaces which belongs
>  		 * to the wpan interface.
>  		 */
> -		if (wdev->ieee802154_ptr->lowpan_dev)
> -			lowpan_dellink(wdev->ieee802154_ptr->lowpan_dev, NULL);
> +		if (wpan_dev->lowpan_dev)
> +			lowpan_dellink(wpan_dev->lowpan_dev, NULL);
>  		break;
>  	default:
>  		return NOTIFY_DONE;
>
Stefan Schmidt March 6, 2018, 12:56 p.m. | #2
Hello.


On 03/05/2018 05:51 PM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> A tun device type can trivially be set to arbitrary value using
> TUNSETLINK ioctl().
>
> Therefore, lowpan_device_event() must really check that ieee802154_ptr
> is not NULL.
>
> Fixes: 2c88b5283f60d ("ieee802154: 6lowpan: remove check on null")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Alexander Aring <alex.aring@gmail.com>
> Cc: Stefan Schmidt <stefan@osg.samsung.com>
> Reported-by: syzbot <syzkaller@googlegroups.com>
> ---
>  net/ieee802154/6lowpan/core.c |   12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/net/ieee802154/6lowpan/core.c b/net/ieee802154/6lowpan/core.c
> index 974765b7d92a..e9f0489e4229 100644
> --- a/net/ieee802154/6lowpan/core.c
> +++ b/net/ieee802154/6lowpan/core.c
> @@ -206,9 +206,13 @@ static inline void lowpan_netlink_fini(void)
>  static int lowpan_device_event(struct notifier_block *unused,
>  			       unsigned long event, void *ptr)
>  {
> -	struct net_device *wdev = netdev_notifier_info_to_dev(ptr);
> +	struct net_device *ndev = netdev_notifier_info_to_dev(ptr);

Not sure why you think there is a rename from wdev to ndev necessary.
I see this more of a rolled in cosmetic change, but its not a real problem from my side.

> +	struct wpan_dev *wpan_dev;
>  
> -	if (wdev->type != ARPHRD_IEEE802154)
> +	if (ndev->type != ARPHRD_IEEE802154)
> +		return NOTIFY_DONE;
> +	wpan_dev = ndev->ieee802154_ptr;
> +	if (!wpan_dev)
>  		return NOTIFY_DONE;
>  
>  	switch (event) {
> @@ -217,8 +221,8 @@ static int lowpan_device_event(struct notifier_block *unused,
>  		 * also delete possible lowpan interfaces which belongs
>  		 * to the wpan interface.
>  		 */
> -		if (wdev->ieee802154_ptr->lowpan_dev)
> -			lowpan_dellink(wdev->ieee802154_ptr->lowpan_dev, NULL);
> +		if (wpan_dev->lowpan_dev)
> +			lowpan_dellink(wpan_dev->lowpan_dev, NULL);
>  		break;
>  	default:
>  		return NOTIFY_DONE;
>

Thanks a lot for fixing this and syzbot for finding it.


Acked-by: Stefan Schmidt <stefan@osg.samsung.com>

Dave, could you take this one directly? I have no other patches pending for your net tree (only net-next) and having a pull request for just
this patch does not make much sense.

regards
Stefan Schmidt
Stefan Schmidt March 8, 2018, 4:21 p.m. | #3
Hello Dave.


On 03/06/2018 01:56 PM, Stefan Schmidt wrote:
> Hello.
>
>
> On 03/05/2018 05:51 PM, Eric Dumazet wrote:
>> From: Eric Dumazet <edumazet@google.com>
>>
>> A tun device type can trivially be set to arbitrary value using
>> TUNSETLINK ioctl().
>>
>> Therefore, lowpan_device_event() must really check that ieee802154_ptr
>> is not NULL.
>>
>> Fixes: 2c88b5283f60d ("ieee802154: 6lowpan: remove check on null")
>> Signed-off-by: Eric Dumazet <edumazet@google.com>
>> Cc: Alexander Aring <alex.aring@gmail.com>
>> Cc: Stefan Schmidt <stefan@osg.samsung.com>
>> Reported-by: syzbot <syzkaller@googlegroups.com>
>> ---
>>  net/ieee802154/6lowpan/core.c |   12 ++++++++----
>>  1 file changed, 8 insertions(+), 4 deletions(-)
>>
>> diff --git a/net/ieee802154/6lowpan/core.c b/net/ieee802154/6lowpan/core.c
>> index 974765b7d92a..e9f0489e4229 100644
>> --- a/net/ieee802154/6lowpan/core.c
>> +++ b/net/ieee802154/6lowpan/core.c
>> @@ -206,9 +206,13 @@ static inline void lowpan_netlink_fini(void)
>>  static int lowpan_device_event(struct notifier_block *unused,
>>  			       unsigned long event, void *ptr)
>>  {
>> -	struct net_device *wdev = netdev_notifier_info_to_dev(ptr);
>> +	struct net_device *ndev = netdev_notifier_info_to_dev(ptr);
> Not sure why you think there is a rename from wdev to ndev necessary.
> I see this more of a rolled in cosmetic change, but its not a real problem from my side.
>
>> +	struct wpan_dev *wpan_dev;
>>  
>> -	if (wdev->type != ARPHRD_IEEE802154)
>> +	if (ndev->type != ARPHRD_IEEE802154)
>> +		return NOTIFY_DONE;
>> +	wpan_dev = ndev->ieee802154_ptr;
>> +	if (!wpan_dev)
>>  		return NOTIFY_DONE;
>>  
>>  	switch (event) {
>> @@ -217,8 +221,8 @@ static int lowpan_device_event(struct notifier_block *unused,
>>  		 * also delete possible lowpan interfaces which belongs
>>  		 * to the wpan interface.
>>  		 */
>> -		if (wdev->ieee802154_ptr->lowpan_dev)
>> -			lowpan_dellink(wdev->ieee802154_ptr->lowpan_dev, NULL);
>> +		if (wpan_dev->lowpan_dev)
>> +			lowpan_dellink(wpan_dev->lowpan_dev, NULL);
>>  		break;
>>  	default:
>>  		return NOTIFY_DONE;
>>
> Thanks a lot for fixing this and syzbot for finding it.
>
>
> Acked-by: Stefan Schmidt <stefan@osg.samsung.com>
>
> Dave, could you take this one directly? I have no other patches pending for your net tree (only net-next) and having a pull request for just
> this patch does not make much sense.
>

Did you miss this or would you prefer if I do a pull request for this single patch?
Either way would be fine with me.

regards
Stefan Schmidt
David Miller March 9, 2018, 4:19 p.m. | #4
From: Stefan Schmidt <stefan@osg.samsung.com>
Date: Thu, 8 Mar 2018 17:21:49 +0100

> Did you miss this or would you prefer if I do a pull request for
> this single patch?  Either way would be fine with me.

Sorry, this escaped me.

Applied and queued up for -stable, thanks.

Patch

diff --git a/net/ieee802154/6lowpan/core.c b/net/ieee802154/6lowpan/core.c
index 974765b7d92a..e9f0489e4229 100644
--- a/net/ieee802154/6lowpan/core.c
+++ b/net/ieee802154/6lowpan/core.c
@@ -206,9 +206,13 @@  static inline void lowpan_netlink_fini(void)
 static int lowpan_device_event(struct notifier_block *unused,
 			       unsigned long event, void *ptr)
 {
-	struct net_device *wdev = netdev_notifier_info_to_dev(ptr);
+	struct net_device *ndev = netdev_notifier_info_to_dev(ptr);
+	struct wpan_dev *wpan_dev;
 
-	if (wdev->type != ARPHRD_IEEE802154)
+	if (ndev->type != ARPHRD_IEEE802154)
+		return NOTIFY_DONE;
+	wpan_dev = ndev->ieee802154_ptr;
+	if (!wpan_dev)
 		return NOTIFY_DONE;
 
 	switch (event) {
@@ -217,8 +221,8 @@  static int lowpan_device_event(struct notifier_block *unused,
 		 * also delete possible lowpan interfaces which belongs
 		 * to the wpan interface.
 		 */
-		if (wdev->ieee802154_ptr->lowpan_dev)
-			lowpan_dellink(wdev->ieee802154_ptr->lowpan_dev, NULL);
+		if (wpan_dev->lowpan_dev)
+			lowpan_dellink(wpan_dev->lowpan_dev, NULL);
 		break;
 	default:
 		return NOTIFY_DONE;