Bluetooth: never linger on process exit

If the current process is exiting, lingering on socket close will make
it unkillable, so we should avoid it.

Reproducer:

  #include <sys/types.h>
  #include <sys/socket.h>

  #define BTPROTO_L2CAP   0
  #define BTPROTO_SCO     2
  #define BTPROTO_RFCOMM  3

  int main()
  {
          int fd;
          struct linger ling;

          fd = socket(PF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM);
          //or: fd = socket(PF_BLUETOOTH, SOCK_DGRAM, BTPROTO_L2CAP);
          //or: fd = socket(PF_BLUETOOTH, SOCK_SEQPACKET, BTPROTO_SCO);

          ling.l_onoff = 1;
          ling.l_linger = 1000000000;
          setsockopt(fd, SOL_SOCKET, SO_LINGER, &ling, sizeof(ling));

          return 0;
  }

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Cc: stable@vger.kernel.org

1 files changed, 2 insertions, 1 deletions

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 9bb4d1b3a483..0bc67dc5dcce 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -1112,7 +1112,8 @@ static int l2cap_sock_shutdown(struct socket *sock, int how)
                 l2cap_chan_close(chan, 0);
                 lock_sock(sk);
 
-                if (sock_flag(sk, SOCK_LINGER) && sk->sk_lingertime)
+                if (sock_flag(sk, SOCK_LINGER) && sk->sk_lingertime &&
+                    !(current->flags & PF_EXITING))
                         err = bt_sock_wait_state(sk, BT_CLOSED,
                                                  sk->sk_lingertime);
         }