From: Hillf Danton <hdanton@xxxxxxxx>
[ Upstream commit 2a154903cec20fb64ff4d7d617ca53c16f8fd53a ]
Prefetch channel before killing sock in order to fix UAF like
BUG: KASAN: use-after-free in l2cap_sock_release+0x24c/0x290 net/bluetooth/l2cap_sock.c:1212
Read of size 8 at addr ffff8880944904a0 by task syz-fuzzer/9751
Reported-by: syzbot+c3c5bdea7863886115dc@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 6c08fc896b60 ("Bluetooth: Fix refcount use-after-free issue")
Cc: Manish Mandlik <mmandlik@xxxxxxxxxx>
Signed-off-by: Hillf Danton <hdanton@xxxxxxxx>
Signed-off-by: Marcel Holtmann <marcel@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/bluetooth/l2cap_sock.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index d128750e47305..5572042f04531 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -1190,6 +1190,7 @@ static int l2cap_sock_release(struct socket *sock)
{
struct sock *sk = sock->sk;
int err;
+ struct l2cap_chan *chan;
BT_DBG("sock %p, sk %p", sock, sk);
@@ -1199,15 +1200,16 @@ static int l2cap_sock_release(struct socket *sock)
bt_sock_unlink(&l2cap_sk_list, sk);
err = l2cap_sock_shutdown(sock, 2);
+ chan = l2cap_pi(sk)->chan;
- l2cap_chan_hold(l2cap_pi(sk)->chan);
- l2cap_chan_lock(l2cap_pi(sk)->chan);
+ l2cap_chan_hold(chan);
+ l2cap_chan_lock(chan);
sock_orphan(sk);
l2cap_sock_kill(sk);
- l2cap_chan_unlock(l2cap_pi(sk)->chan);
- l2cap_chan_put(l2cap_pi(sk)->chan);
+ l2cap_chan_unlock(chan);
+ l2cap_chan_put(chan);
return err;
}
--
2.25.1
