linux-kernel - Re: [PATCH] Bluetooth: Fix use after free in l2cap_chan

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Date:	Wed, 18 Mar 2015 17:22:36 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Harish Jenny K N <harish_kandiga@...tor.com>, marcel@...tmann.org
CC:	gustavo@...ovan.org, johan.hedberg@...il.com, davem@...emloft.net,
	linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Bluetooth: Fix use after free in l2cap_chan_timeout

Hello.

On 3/18/2015 2:59 PM, Harish Jenny K N wrote:

> There is a potential use after free in bt_sock_poll when a
> socket gets killed without getting unlinked from accept_q.
> Hence added code to unlink from accpept_q by calling teardown
> before freeing the socket for channel type L2CAP_CHAN_CONN_ORIENTED.

> Signed-off-by: Harish Jenny K N <harish_kandiga@...tor.com>
> ---
>   net/bluetooth/l2cap_core.c |    5 +++++
>   1 file changed, 5 insertions(+)

> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> index 6ba33f9..3c3421e 100644
> --- a/net/bluetooth/l2cap_core.c
> +++ b/net/bluetooth/l2cap_core.c
> @@ -415,6 +415,11 @@ static void l2cap_chan_timeout(struct work_struct *work)
>
>   	l2cap_chan_close(chan, reason);
>
> +	if (((chan->state == BT_CONNECTED) || (chan->state == BT_CONFIG)) &&

    Note that parens around == are unnecessary.

> +	    chan->chan_type == L2CAP_CHAN_CONN_ORIENTED) {
> +		chan->ops->teardown(chan, 0);
> +	}
> +
[...]

WBR, Sergei

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