Messages in this thread | | | Subject | Re: [PATCH 1/2] Bluetooth: call sock_hold earlier in sco_conn_del | From | Desmond Cheong Zhi Xi <> | Date | Mon, 4 Oct 2021 14:12:07 -0400 |
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Hi Marcel,
On 10/9/21 3:36 am, Marcel Holtmann wrote: > Hi Desmond, > >> In sco_conn_del, conn->sk is read while holding on to the >> sco_conn.lock to avoid races with a socket that could be released >> concurrently. >> >> However, in between unlocking sco_conn.lock and calling sock_hold, >> it's possible for the socket to be freed, which would cause a >> use-after-free write when sock_hold is finally called. >> >> To fix this, the reference count of the socket should be increased >> while the sco_conn.lock is still held. >> >> Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com> >> --- >> net/bluetooth/sco.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c >> index b62c91c627e2..4a057f99b60a 100644 >> --- a/net/bluetooth/sco.c >> +++ b/net/bluetooth/sco.c >> @@ -187,10 +187,11 @@ static void sco_conn_del(struct hci_conn *hcon, int err) >> /* Kill socket */ >> sco_conn_lock(conn); >> sk = conn->sk; > > please add a comment here on why we are doing it. >
So sorry for the very delayed response. I was looking through old email threads to check if my recently resent patch was still necessary, and just realized I missed this email.
This patch was merged into the bluetooth-next tree before your feedback came in. Would you still like me to write a separate patch to add the requested comment?
Best wishes, Desmond
>> + if (sk) >> + sock_hold(sk); >> sco_conn_unlock(conn); >> >> if (sk) { >> - sock_hold(sk); >> lock_sock(sk); >> sco_sock_clear_timer(sk); >> sco_chan_del(sk, err); > > Regards > > Marcel >
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