This change prevents a use-after-free caused by one of the worker
threads starting up (see below) *after* the final channel reference
has been put() during sock_close() but *before* the references to the
channel have been 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@xxxxxxxxxx
Cc: Marcel Holtmann <marcel@xxxxxxxxxxxx>
Cc: Johan Hedberg <johan.hedberg@xxxxxxxxx>
Cc: Luiz Augusto von Dentz <luiz.dentz@xxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
Cc: linux-bluetooth@xxxxxxxxxxxxxxx
Cc: netdev@xxxxxxxxxxxxxxx
Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
---
net/bluetooth/l2cap_core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index ae78490ecd3d4..82279c5919fd8 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -483,9 +483,7 @@ static void l2cap_chan_destroy(struct kref *kref)
BT_DBG("chan %p", chan);
- write_lock(&chan_list_lock);
list_del(&chan->global_l);
- write_unlock(&chan_list_lock);
kfree(chan);
}
@@ -501,7 +499,9 @@ void l2cap_chan_put(struct l2cap_chan *c)
{
BT_DBG("chan %p orig refcnt %u", c, kref_read(&c->kref));
+ write_lock(&chan_list_lock);
kref_put(&c->kref, l2cap_chan_destroy);
+ write_unlock(&chan_list_lock);
}
EXPORT_SYMBOL_GPL(l2cap_chan_put);
--
2.36.1.255.ge46751e96f-goog
