2023-03-13 09:11:47

by Jiasheng Jiang

Subject: [PATCH] Bluetooth: 6LoWPAN: Add missing check for skb_clone

Add the check for the return value of skb_clone since it may return NULL
pointer and cause NULL pointer dereference in send_pkt.

Fixes: 18722c247023 ("Bluetooth: Enable 6LoWPAN support for BT LE devices")
Signed-off-by: Jiasheng Jiang <[email protected]>
---
net/bluetooth/6lowpan.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c
index 4eb1b3ced0d2..bf42a0b03e20 100644
--- a/net/bluetooth/6lowpan.c
+++ b/net/bluetooth/6lowpan.c
@@ -477,6 +477,10 @@ static int send_mcast_pkt(struct sk_buff *skb, struct net_device *netdev)
int ret;

local_skb = skb_clone(skb, GFP_ATOMIC);
+ if (!local_skb) {
+ rcu_read_unlock();
+ return -ENOMEM;
+ }

BT_DBG("xmit %s to %pMR type %u IP %pI6c chan %p",
netdev->name,
--
2.25.1

2023-03-14 14:58:44

by Simon Horman

Subject: Re: [PATCH] Bluetooth: 6LoWPAN: Add missing check for skb_clone

On Mon, Mar 13, 2023 at 05:03:46PM +0800, Jiasheng Jiang wrote:
> Add the check for the return value of skb_clone since it may return NULL
> pointer and cause NULL pointer dereference in send_pkt.
>
> Fixes: 18722c247023 ("Bluetooth: Enable 6LoWPAN support for BT LE devices")
> Signed-off-by: Jiasheng Jiang <[email protected]>
> ---
> net/bluetooth/6lowpan.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c
> index 4eb1b3ced0d2..bf42a0b03e20 100644
> --- a/net/bluetooth/6lowpan.c
> +++ b/net/bluetooth/6lowpan.c
> @@ -477,6 +477,10 @@ static int send_mcast_pkt(struct sk_buff *skb, struct net_device *netdev)
> int ret;
>
> local_skb = skb_clone(skb, GFP_ATOMIC);
> + if (!local_skb) {
> + rcu_read_unlock();
> + return -ENOMEM;
> + }

Further down in this loop an error is handled as follows,
I wonder if that pattern is appropriate here too.

ret = send_pkt(pentry->chan, local_skb, netdev);
if (ret < 0)
err = ret;

> BT_DBG("xmit %s to %pMR type %u IP %pI6c chan %p",
> netdev->name,
> --
> 2.25.1
>

2023-03-15 07:03:19

by Jiasheng Jiang

Subject: Re: Re: [PATCH] Bluetooth: 6LoWPAN: Add missing check for skb_clone

On Tue, Mar 14, 2023 at 10:58:23PM +0800, Simon Horman wrote:
>On Mon, Mar 13, 2023 at 05:03:46PM +0800, Jiasheng Jiang wrote:
>> Add the check for the return value of skb_clone since it may return NULL
>> pointer and cause NULL pointer dereference in send_pkt.
>>
>> Fixes: 18722c247023 ("Bluetooth: Enable 6LoWPAN support for BT LE devices")
>> Signed-off-by: Jiasheng Jiang <[email protected]>
>> ---
>> net/bluetooth/6lowpan.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c
>> index 4eb1b3ced0d2..bf42a0b03e20 100644
>> --- a/net/bluetooth/6lowpan.c
>> +++ b/net/bluetooth/6lowpan.c
>> @@ -477,6 +477,10 @@ static int send_mcast_pkt(struct sk_buff *skb, struct net_device *netdev)
>> int ret;
>>
>> local_skb = skb_clone(skb, GFP_ATOMIC);
>> + if (!local_skb) {
>> + rcu_read_unlock();
>> + return -ENOMEM;
>> + }
>
> Further down in this loop an error is handled as follows,
> I wonder if that pattern is appropriate here too.
>
> ret = send_pkt(pentry->chan, local_skb, netdev);
> if (ret < 0)
> err = ret;
>

I think it should be better to return error here in order to avoid the
error being overwritten.
I will submit a v2 to modify the error handling here.

Thanks,
Jiang