Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 098e07ef authored by Luiz Augusto von Dentz's avatar Luiz Augusto von Dentz Committed by Greg Kroah-Hartman
Browse files

Bluetooth: L2CAP: Fix use-after-free caused by l2cap_chan_put 



commit d0be8347c623e0ac4202a1d4e0373882821f56b0 upstream.

This fixes the following trace which is caused by hci_rx_work starting up
*after* the final channel reference has been put() during sock_close() but
*before* the references to the channel have been destroyed, so instead
the code now rely on kref_get_unless_zero/l2cap_chan_hold_unless_zero to
prevent referencing a channel that is about to be destroyed.

  refcount_t: increment on 0; use-after-free.
  BUG: KASAN: use-after-free in refcount_dec_and_test+0x20/0xd0
  Read of size 4 at addr ffffffc114f5bf18 by task kworker/u17:14/705

  CPU: 4 PID: 705 Comm: kworker/u17:14 Tainted: G S      W
  4.14.234-00003-g1fb6d0bd49a4-dirty #28
  Hardware name: Qualcomm Technologies, Inc. SM8150 V2 PM8150
  Google Inc. MSM sm8150 Flame DVT (DT)
  Workqueue: hci0 hci_rx_work
  Call trace:
   dump_backtrace+0x0/0x378
   show_stack+0x20/0x2c
   dump_stack+0x124/0x148
   print_address_description+0x80/0x2e8
   __kasan_report+0x168/0x188
   kasan_report+0x10/0x18
   __asan_load4+0x84/0x8c
   refcount_dec_and_test+0x20/0xd0
   l2cap_chan_put+0x48/0x12c
   l2cap_recv_frame+0x4770/0x6550
   l2cap_recv_acldata+0x44c/0x7a4
   hci_acldata_packet+0x100/0x188
   hci_rx_work+0x178/0x23c
   process_one_work+0x35c/0x95c
   worker_thread+0x4cc/0x960
   kthread+0x1a8/0x1c4
   ret_from_fork+0x10/0x18

Cc: stable@kernel.org
Reported-by: default avatarLee Jones <lee.jones@linaro.org>
Signed-off-by: default avatarLuiz Augusto von Dentz <luiz.von.dentz@intel.com>
Tested-by: default avatarLee Jones <lee.jones@linaro.org>
Signed-off-by: default avatarLuiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 77ba2b9b

include/net/bluetooth/l2cap.h

+1 −0
Original line number Diff line number Diff line
@@ -802,6 +802,7 @@ enum { 
};



void l2cap_chan_hold(struct l2cap_chan *c);

struct l2cap_chan *l2cap_chan_hold_unless_zero(struct l2cap_chan *c);

void l2cap_chan_put(struct l2cap_chan *c);



static inline void l2cap_chan_lock(struct l2cap_chan *chan)

net/bluetooth/l2cap_core.c

+48 −13
Original line number Diff line number Diff line
@@ -110,7 +110,8 @@ static struct l2cap_chan *__l2cap_get_chan_by_scid(struct l2cap_conn *conn, 
}



/* Find channel with given SCID.

 * Returns locked channel. */

 * Returns a reference locked channel.

 */

static struct l2cap_chan *l2cap_get_chan_by_scid(struct l2cap_conn *conn,

						 u16 cid)

{
@@ -118,15 +119,19 @@ static struct l2cap_chan *l2cap_get_chan_by_scid(struct l2cap_conn *conn, 


	mutex_lock(&conn->chan_lock);

	c = __l2cap_get_chan_by_scid(conn, cid);

	if (c) {

		/* Only lock if chan reference is not 0 */

		c = l2cap_chan_hold_unless_zero(c);

		if (c)

			l2cap_chan_lock(c);

	}

	mutex_unlock(&conn->chan_lock);



	return c;

}



/* Find channel with given DCID.

 * Returns locked channel.

 * Returns a reference locked channel.

 */

static struct l2cap_chan *l2cap_get_chan_by_dcid(struct l2cap_conn *conn,

						 u16 cid)
@@ -135,8 +140,12 @@ static struct l2cap_chan *l2cap_get_chan_by_dcid(struct l2cap_conn *conn, 


	mutex_lock(&conn->chan_lock);

	c = __l2cap_get_chan_by_dcid(conn, cid);

	if (c) {

		/* Only lock if chan reference is not 0 */

		c = l2cap_chan_hold_unless_zero(c);

		if (c)

			l2cap_chan_lock(c);

	}

	mutex_unlock(&conn->chan_lock);



	return c;
@@ -161,8 +170,12 @@ static struct l2cap_chan *l2cap_get_chan_by_ident(struct l2cap_conn *conn, 


	mutex_lock(&conn->chan_lock);

	c = __l2cap_get_chan_by_ident(conn, ident);

	if (c) {

		/* Only lock if chan reference is not 0 */

		c = l2cap_chan_hold_unless_zero(c);

		if (c)

			l2cap_chan_lock(c);

	}

	mutex_unlock(&conn->chan_lock);



	return c;
@@ -496,6 +509,16 @@ void l2cap_chan_hold(struct l2cap_chan *c) 
	kref_get(&c->kref);

}



struct l2cap_chan *l2cap_chan_hold_unless_zero(struct l2cap_chan *c)

{

	BT_DBG("chan %p orig refcnt %u", c, kref_read(&c->kref));



	if (!kref_get_unless_zero(&c->kref))

		return NULL;



	return c;

}



void l2cap_chan_put(struct l2cap_chan *c)

{

	BT_DBG("chan %p orig refcnt %d", c, kref_read(&c->kref));
@@ -1812,7 +1835,10 @@ static struct l2cap_chan *l2cap_global_chan_by_psm(int state, __le16 psm, 
			src_match = !bacmp(&c->src, src);

			dst_match = !bacmp(&c->dst, dst);

			if (src_match && dst_match) {

				l2cap_chan_hold(c);

				c = l2cap_chan_hold_unless_zero(c);

				if (!c)

					continue;



				read_unlock(&chan_list_lock);

				return c;

			}
@@ -1827,7 +1853,7 @@ static struct l2cap_chan *l2cap_global_chan_by_psm(int state, __le16 psm, 
	}



	if (c1)

		l2cap_chan_hold(c1);

		c1 = l2cap_chan_hold_unless_zero(c1);



	read_unlock(&chan_list_lock);
@@ -4221,6 +4247,7 @@ static inline int l2cap_config_req(struct l2cap_conn *conn, 


unlock:

	l2cap_chan_unlock(chan);

	l2cap_chan_put(chan);

	return err;

}
@@ -4334,6 +4361,7 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn, 


done:

	l2cap_chan_unlock(chan);

	l2cap_chan_put(chan);

	return err;

}
@@ -5062,6 +5090,7 @@ static inline int l2cap_move_channel_req(struct l2cap_conn *conn, 
	l2cap_send_move_chan_rsp(chan, result);



	l2cap_chan_unlock(chan);

	l2cap_chan_put(chan);



	return 0;

}
@@ -5154,6 +5183,7 @@ static void l2cap_move_continue(struct l2cap_conn *conn, u16 icid, u16 result) 
	}



	l2cap_chan_unlock(chan);

	l2cap_chan_put(chan);

}



static void l2cap_move_fail(struct l2cap_conn *conn, u8 ident, u16 icid,
@@ -5183,6 +5213,7 @@ static void l2cap_move_fail(struct l2cap_conn *conn, u8 ident, u16 icid, 
	l2cap_send_move_chan_cfm(chan, L2CAP_MC_UNCONFIRMED);



	l2cap_chan_unlock(chan);

	l2cap_chan_put(chan);

}



static int l2cap_move_channel_rsp(struct l2cap_conn *conn,
@@ -5246,6 +5277,7 @@ static int l2cap_move_channel_confirm(struct l2cap_conn *conn, 
	l2cap_send_move_chan_cfm_rsp(conn, cmd->ident, icid);



	l2cap_chan_unlock(chan);

	l2cap_chan_put(chan);



	return 0;

}
@@ -5281,6 +5313,7 @@ static inline int l2cap_move_channel_confirm_rsp(struct l2cap_conn *conn, 
	}



	l2cap_chan_unlock(chan);

	l2cap_chan_put(chan);



	return 0;

}
@@ -5653,12 +5686,11 @@ static inline int l2cap_le_credits(struct l2cap_conn *conn, 
	if (credits > max_credits) {

		BT_ERR("LE credits overflow");

		l2cap_send_disconn_req(chan, ECONNRESET);

		l2cap_chan_unlock(chan);



		/* Return 0 so that we don't trigger an unnecessary

		 * command reject packet.

		 */

		return 0;

		goto unlock;

	}



	chan->tx_credits += credits;
@@ -5669,7 +5701,9 @@ static inline int l2cap_le_credits(struct l2cap_conn *conn, 
	if (chan->tx_credits)

		chan->ops->resume(chan);



unlock:

	l2cap_chan_unlock(chan);

	l2cap_chan_put(chan);



	return 0;

}
@@ -6983,6 +7017,7 @@ static void l2cap_data_channel(struct l2cap_conn *conn, u16 cid, 


done:

	l2cap_chan_unlock(chan);

	l2cap_chan_put(chan);

}



static void l2cap_conless_channel(struct l2cap_conn *conn, __le16 psm,
@@ -7386,7 +7421,7 @@ static struct l2cap_chan *l2cap_global_fixed_chan(struct l2cap_chan *c, 
		if (src_type != c->src_type)

			continue;



		l2cap_chan_hold(c);

		c = l2cap_chan_hold_unless_zero(c);

		read_unlock(&chan_list_lock);

		return c;

	}