linux-kernel - Re: [PATCH] Bluetooth: sco: Fix lock_sock() blockage by memcpy_from

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Message-Id: <28F3A4FF-A9F0-40DB-8D90-FF04E3445CC5@holtmann.org>
Date:   Mon, 30 Aug 2021 16:49:01 +0200
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        Johan Hedberg <johan.hedberg@...il.com>,
        "open list:BLUETOOTH SUBSYSTEM" <linux-bluetooth@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Bluetooth: sco: Fix lock_sock() blockage by
 memcpy_from_msg()

Hi Takashi,

> The sco_send_frame() also takes lock_sock() during memcpy_from_msg()
> call that may be endlessly blocked by a task with userfaultd
> technique, and this will result in a hung task watchdog trigger.
> 
> Just like the similar fix for hci_sock_sendmsg() in commit
> 92c685dc5de0 ("Bluetooth: reorganize functions..."), this patch moves
> the  memcpy_from_msg() out of lock_sock() for addressing the hang.
> 
> This should be the last piece for fixing CVE-2021-3640 after a few
> already queued fixes.
> 
> Signed-off-by: Takashi Iwai <tiwai@...e.de>
> ---
> net/bluetooth/sco.c | 23 +++++++++++++++--------
> 1 file changed, 15 insertions(+), 8 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel