Re: Kernel panic observed during sco-connection-disconnection

[Johan Hedberg <johan.hedberg@gmail.com>]

Hi Syam,

On Fri, Oct 23, 2015, s.syam@samsung.com wrote:
> We have observed one kernel panic during the sco close.
> The panic logs has been given below. Further analysis we could see that  invalid memory access is happening at 
> sco_pi(sk)->conn->hcon = NULL; in __sco_sock_close().
> 
> It will be great if someone analyses and provide the fix/clue for this issue.
> Thanks for your time.
> 
> 
> Code:
> static void __sco_sock_close(struct sock *sk)
> {
> 	BT_DBG("sk %p state %d socket %p", sk, sk->sk_state, sk->sk_socket);
> 
> 	switch (sk->sk_state) {
> 	case BT_LISTEN:
> 		sco_sock_cleanup_listen(sk);
> 		break;
> 
> 	case BT_CONNECTED:
> 	case BT_CONFIG:
> 		if (sco_pi(sk)->conn->hcon) {
> 			sk->sk_state = BT_DISCONN;
> 			sco_sock_set_timer(sk, SCO_DISCONN_TIMEOUT);
> 			hci_conn_drop(sco_pi(sk)->conn->hcon);  
> 			sco_pi(sk)->conn->hcon = NULL; //Invalid memory access happen here.
> 		} else
> 			sco_chan_del(sk, ECONNRESET);
> 		break;
> 
> 	case BT_CONNECT2:
> 	case BT_CONNECT:
> 	case BT_DISCONN:
> ...
> ...
> 	}
> }
> 
> Logs:
> Oct 21 23:35:12 alert Kernel: [  175.323507] Unable to handle kernel NULL pointer dereference at virtual address 00000000
> .....
> Oct 21 23:35:12 warn Kernel: [  175.338344] [<c0866be4>] (__sco_sock_close+0x1ec/0x230) from [<c0866d20>] (sco_sock_close+0x20/0x34)
> Oct 21 23:35:12 warn Kernel: [  175.338478] [<c0866d20>] (sco_sock_close+0x20/0x34) from [<c0866d78>] (sco_sock_release+0x44/0x100)
> Oct 21 23:35:12 warn Kernel: [  175.338614] [<c0866d78>] (sco_sock_release+0x44/0x100) from [<c0721ad0>] (sock_release+0x20/0xc4)
> Oct 21 23:35:12 warn Kernel: [  175.338745] [<c0721ad0>] (sock_release+0x20/0xc4) from [<c07221e4>] (sock_close+0x20/0x2c)
> Oct 21 23:35:12 warn Kernel: [  175.338874] [<c07221e4>] (sock_close+0x20/0x2c) from [<c02741d0>] (fput+0x11c/0x230)
> Oct 21 23:35:12 warn Kernel: [  175.338994] [<c02741d0>] (fput+0x11c/0x230) from [<c0270fa8>] (filp_close+0x70/0x7c)
> Oct 21 23:35:12 warn Kernel: [  175.339110] [<c0270fa8>] (filp_close+0x70/0x7c) from [<c0271064>] (sys_close+0xb0/0xf0)
> Oct 21 23:35:12 warn Kernel: [  175.339232] [<c0271064>] (sys_close+0xb0/0xf0) from [<c0105d9c>] (__sys_trace_return+0x0/0x24) 

You'll probably want to take a look at the SCO socket patch set that
Kuba sent in the beginning of this month:

	[PATCH 0/5] Few proposed fixes to stop crashes on fast SCO disconnec

Particularly his second patch looks like something that could be related
to this.

Johan