From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: Marcel Holtmann <marcel@holtmann.org>,
Johan Hedberg <johan.hedberg@gmail.com>,
Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
linux-bluetooth@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>, Lin Ma <linma@zju.edu.cn>,
netdev@vger.kernel.org
Subject: [PATCH v3] Bluetooth: call lock_sock() outside of spinlock section
Date: Tue, 13 Jul 2021 20:27:49 +0900 [thread overview]
Message-ID: <48d66166-4d39-4fe2-3392-7e0c84b9bdb3@i-love.sakura.ne.jp> (raw)
In-Reply-To: <9deece33-5d7f-9dcb-9aaa-94c60d28fc9a@i-love.sakura.ne.jp>
syzbot is hitting might_sleep() warning at hci_sock_dev_event() due to
calling lock_sock() with rw spinlock held [1]. Among three possible
approaches [2], this patch chose holding a refcount via sock_hold() and
revalidating the element via sk_hashed().
Link: https://syzkaller.appspot.com/bug?extid=a5df189917e79d5e59c9 [1]
Link: https://lkml.kernel.org/r/05535d35-30d6-28b6-067e-272d01679d24@i-love.sakura.ne.jp [2]
Reported-by: syzbot <syzbot+a5df189917e79d5e59c9@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: syzbot <syzbot+a5df189917e79d5e59c9@syzkaller.appspotmail.com>
Fixes: e305509e678b3a4a ("Bluetooth: use correct lock to prevent UAF of hdev object")
---
Changes in v3:
Don't use unlocked hci_pi(sk)->hdev != hdev test, for it is racy.
No need to defer hci_dev_put(hdev), for it can't be the last reference.
Changes in v2:
Take hci_sk_list.lock for write in case bt_sock_unlink() is called after
sk_hashed(sk) test, and defer hci_dev_put(hdev) till schedulable context.
net/bluetooth/hci_sock.c | 30 +++++++++++++++++++++++++++++-
1 file changed, 29 insertions(+), 1 deletion(-)
diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
index b04a5a02ecf3..786a06a232fd 100644
--- a/net/bluetooth/hci_sock.c
+++ b/net/bluetooth/hci_sock.c
@@ -760,10 +760,18 @@ void hci_sock_dev_event(struct hci_dev *hdev, int event)
struct sock *sk;
/* Detach sockets from device */
+restart:
read_lock(&hci_sk_list.lock);
sk_for_each(sk, &hci_sk_list.head) {
+ /* This sock_hold(sk) is safe, for bt_sock_unlink(sk)
+ * is not called yet.
+ */
+ sock_hold(sk);
+ read_unlock(&hci_sk_list.lock);
lock_sock(sk);
- if (hci_pi(sk)->hdev == hdev) {
+ write_lock(&hci_sk_list.lock);
+ /* Check that bt_sock_unlink(sk) is not called yet. */
+ if (sk_hashed(sk) && hci_pi(sk)->hdev == hdev) {
hci_pi(sk)->hdev = NULL;
sk->sk_err = EPIPE;
sk->sk_state = BT_OPEN;
@@ -771,7 +779,27 @@ void hci_sock_dev_event(struct hci_dev *hdev, int event)
hci_dev_put(hdev);
}
+ write_unlock(&hci_sk_list.lock);
release_sock(sk);
+ read_lock(&hci_sk_list.lock);
+ /* If bt_sock_unlink(sk) is not called yet, we can
+ * continue iteration. We can use __sock_put(sk) here
+ * because hci_sock_release() will call sock_put(sk)
+ * after bt_sock_unlink(sk).
+ */
+ if (sk_hashed(sk)) {
+ __sock_put(sk);
+ continue;
+ }
+ /* Otherwise, we need to restart iteration, for the
+ * next socket pointed by sk->next might be already
+ * gone. We can't use __sock_put(sk) here because
+ * hci_sock_release() might have already called
+ * sock_put(sk) after bt_sock_unlink(sk).
+ */
+ read_unlock(&hci_sk_list.lock);
+ sock_put(sk);
+ goto restart;
}
read_unlock(&hci_sk_list.lock);
}
--
2.18.4
next prev parent reply other threads:[~2021-07-13 11:28 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-27 13:11 [PATCH] Bluetooth: call lock_sock() outside of spinlock section Tetsuo Handa
2021-06-27 14:05 ` bluez.test.bot
2021-07-07 9:43 ` [PATCH v2] " Tetsuo Handa
2021-07-07 10:08 ` [v2] " bluez.test.bot
2021-07-07 18:20 ` [PATCH v2] " Luiz Augusto von Dentz
2021-07-07 23:33 ` Tetsuo Handa
2021-07-08 1:00 ` LinMa
2021-07-09 13:50 ` Tetsuo Handa
2021-07-10 13:34 ` Tetsuo Handa
2021-07-08 7:16 ` [v2] " bluez.test.bot
2021-07-13 11:27 ` Tetsuo Handa [this message]
2021-07-13 11:57 ` [v3] " bluez.test.bot
2021-07-14 19:20 ` [PATCH v3] " Luiz Augusto von Dentz
2021-07-15 3:03 ` LinMa
2021-07-16 3:47 ` Desmond Cheong Zhi Xi
2021-07-16 4:11 ` Desmond Cheong Zhi Xi
2021-07-16 14:48 ` Tetsuo Handa
2021-07-16 15:26 ` LinMa
2021-07-17 15:41 ` Yet Another Patch for CVE-2021-3573 LinMa
2021-07-17 15:45 ` LinMa
2021-07-22 9:36 ` [PATCH v3] Bluetooth: call lock_sock() outside of spinlock section Tetsuo Handa
2021-07-22 4:47 ` LinMa
2021-07-22 5:16 ` Tetsuo Handa
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