Netdev Archive on lore.kernel.org
help / color / mirror / Atom feed
* [PATCH] Bluetooth: call lock_sock() outside of spinlock section
@ 2021-06-27 13:11 Tetsuo Handa
  2021-07-07  9:43 ` [PATCH v2] " Tetsuo Handa
  0 siblings, 1 reply; 19+ messages in thread
From: Tetsuo Handa @ 2021-06-27 13:11 UTC (permalink / raw)
  To: Marcel Holtmann, Johan Hedberg, Luiz Augusto von Dentz, linux-bluetooth
  Cc: David S. Miller, Jakub Kicinski, Lin Ma, netdev, Tetsuo Handa

syzbot is hitting might_sleep() warning at hci_sock_dev_event() due to
calling lock_sock() with rw spinlock held [1]. Defer calling lock_sock()
via sock_hold().

Link: https://syzkaller.appspot.com/bug?extid=a5df189917e79d5e59c9 [1]
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")
---
 net/bluetooth/hci_sock.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
index eed0dd066e12..64e54ab0892f 100644
--- a/net/bluetooth/hci_sock.c
+++ b/net/bluetooth/hci_sock.c
@@ -759,19 +759,39 @@ void hci_sock_dev_event(struct hci_dev *hdev, int event)
 	if (event == HCI_DEV_UNREG) {
 		struct sock *sk;
 
+restart:
 		/* Detach sockets from device */
 		read_lock(&hci_sk_list.lock);
 		sk_for_each(sk, &hci_sk_list.head) {
+			/* hci_sk_list.lock is preventing hci_sock_release()
+			 * from calling bt_sock_unlink().
+			 */
+			if (hci_pi(sk)->hdev != hdev || sk_unhashed(sk))
+				continue;
+			/* Take a ref because we can't call lock_sock() with
+			 * hci_sk_list.lock held.
+			 */
+			sock_hold(sk);
+			read_unlock(&hci_sk_list.lock);
 			lock_sock(sk);
-			if (hci_pi(sk)->hdev == hdev) {
+			/* Since hci_sock_release() might have already called
+			 * bt_sock_unlink() while waiting for lock_sock(),
+			 * use sk_hashed(sk) for checking that bt_sock_unlink()
+			 * is not yet called.
+			 */
+			if (sk_hashed(sk) && hci_pi(sk)->hdev == hdev) {
 				hci_pi(sk)->hdev = NULL;
 				sk->sk_err = EPIPE;
 				sk->sk_state = BT_OPEN;
 				sk->sk_state_change(sk);
-
 				hci_dev_put(hdev);
 			}
 			release_sock(sk);
+			sock_put(sk);
+			/* Restarting is safe, for hci_pi(sk)->hdev is now NULL
+			 * if condition met and will "continue;" otherwise.
+			 */
+			goto restart;
 		}
 		read_unlock(&hci_sk_list.lock);
 	}
-- 
2.18.4


^ permalink raw reply	[flat|nested] 19+ messages in thread

end of thread, other threads:[~2021-07-22  9:37 UTC | newest]

Thread overview: 19+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-06-27 13:11 [PATCH] Bluetooth: call lock_sock() outside of spinlock section Tetsuo Handa
2021-07-07  9:43 ` [PATCH v2] " Tetsuo Handa
2021-07-07 18:20   ` 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
2021-07-13 11:27   ` [PATCH v3] " Tetsuo Handa
2021-07-14 19:20     ` 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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).