From: Luiz Augusto von Dentz luiz.von.dentz@intel.com
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: Lee Jones lee.jones@linaro.org Signed-off-by: Luiz Augusto von Dentz luiz.von.dentz@intel.com Tested-by: Lee Jones lee.jones@linaro.org Signed-off-by: Luiz Augusto von Dentz luiz.von.dentz@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/net/bluetooth/l2cap.h | 1 net/bluetooth/l2cap_core.c | 61 +++++++++++++++++++++++++++++++++--------- 2 files changed, 49 insertions(+), 13 deletions(-)
--- a/include/net/bluetooth/l2cap.h +++ b/include/net/bluetooth/l2cap.h @@ -798,6 +798,7 @@ 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) --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -113,7 +113,8 @@ static struct l2cap_chan *__l2cap_get_ch }
/* 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) { @@ -121,15 +122,19 @@ static struct l2cap_chan *l2cap_get_chan
mutex_lock(&conn->chan_lock); c = __l2cap_get_chan_by_scid(conn, cid); - if (c) - l2cap_chan_lock(c); + 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) @@ -138,8 +143,12 @@ static struct l2cap_chan *l2cap_get_chan
mutex_lock(&conn->chan_lock); c = __l2cap_get_chan_by_dcid(conn, cid); - if (c) - l2cap_chan_lock(c); + 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; @@ -164,8 +173,12 @@ static struct l2cap_chan *l2cap_get_chan
mutex_lock(&conn->chan_lock); c = __l2cap_get_chan_by_ident(conn, ident); - if (c) - l2cap_chan_lock(c); + 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; @@ -491,6 +504,16 @@ void l2cap_chan_hold(struct l2cap_chan * 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)); @@ -1803,7 +1826,10 @@ static struct l2cap_chan *l2cap_global_c 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; } @@ -1818,7 +1844,7 @@ static struct l2cap_chan *l2cap_global_c }
if (c1) - l2cap_chan_hold(c1); + c1 = l2cap_chan_hold_unless_zero(c1);
read_unlock(&chan_list_lock);
@@ -4204,6 +4230,7 @@ static inline int l2cap_config_req(struc
unlock: l2cap_chan_unlock(chan); + l2cap_chan_put(chan); return err; }
@@ -4316,6 +4343,7 @@ static inline int l2cap_config_rsp(struc
done: l2cap_chan_unlock(chan); + l2cap_chan_put(chan); return err; }
@@ -5044,6 +5072,7 @@ send_move_response: l2cap_send_move_chan_rsp(chan, result);
l2cap_chan_unlock(chan); + l2cap_chan_put(chan);
return 0; } @@ -5136,6 +5165,7 @@ static void l2cap_move_continue(struct l }
l2cap_chan_unlock(chan); + l2cap_chan_put(chan); }
static void l2cap_move_fail(struct l2cap_conn *conn, u8 ident, u16 icid, @@ -5165,6 +5195,7 @@ static void l2cap_move_fail(struct l2cap 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, @@ -5228,6 +5259,7 @@ static int l2cap_move_channel_confirm(st l2cap_send_move_chan_cfm_rsp(conn, cmd->ident, icid);
l2cap_chan_unlock(chan); + l2cap_chan_put(chan);
return 0; } @@ -5263,6 +5295,7 @@ static inline int l2cap_move_channel_con }
l2cap_chan_unlock(chan); + l2cap_chan_put(chan);
return 0; } @@ -5635,12 +5668,11 @@ static inline int l2cap_le_credits(struc 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; @@ -5651,7 +5683,9 @@ static inline int l2cap_le_credits(struc if (chan->tx_credits) chan->ops->resume(chan);
+unlock: l2cap_chan_unlock(chan); + l2cap_chan_put(chan);
return 0; } @@ -6949,6 +6983,7 @@ drop:
done: l2cap_chan_unlock(chan); + l2cap_chan_put(chan); }
static void l2cap_conless_channel(struct l2cap_conn *conn, __le16 psm, @@ -7353,7 +7388,7 @@ static struct l2cap_chan *l2cap_global_f 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; }