Hi Liu, * Liu, Chuansheng <chuansheng.liu@xxxxxxxxx> [2013-01-04 00:55:26 +0000]: > > > > -----Original Message----- > > From: Gustavo Padovan [mailto:gustavo@xxxxxxxxxxx] > > Sent: Friday, January 04, 2013 6:03 AM > > To: Liu, Chuansheng > > Cc: marcel@xxxxxxxxxxxx; johan.hedberg@xxxxxxxxx; > > linux-bluetooth@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > > Subject: Re: [PATCH] Bluetooth: fix the oops due to conn->hcon == NULL in > > shutdown case > > > > Hi Chuansheng, > > > > * Chuansheng Liu <chuansheng.liu@xxxxxxxxx> [2012-12-25 18:04:17 +0800]: > > > > > > > > Meet one panic issue as below stack: > > > > > Disassemble the code: > > > base address of __sco_sock_close is 0xc184f410 > > > 0xc184f4f8 <+232>: lock decl 0x8(%ebx) < == crash here, ebx is 0x0, > > > > > > the related source code is: > > > (gdb) l *0xc184f4f8 > > > 0xc184f4f8 is in __sco_sock_close (arch/x86/include/asm/atomic.h:123) > > > 119 static inline int atomic_dec_and_test(atomic_t *v) > > > 123 asm volatile(LOCK_PREFIX "decl %0; sete %1" > > > > > > The whole call stack is: > > > sys_shutdown() > > > sco_sock_shutdown() > > > __sco_sock_close() > > > hci_conn_put() > > > atomic_dec_and_test() > > > > > > Due to the conn->hcon is NULL, and the member hcon->refcnt is at offset 0x8, > > > so "BUG: unable to handle kernel NULL pointer dereference at 00000008" > > > appears. > Could you add the above crash info to indicate where crashed? Thanks. > > > > > > > Here fix it that adding the condition if conn->hcon is NULL, just like > > > in sco_chan_del(). > > > > > > Signed-off-by: liu chuansheng <chuansheng.liu@xxxxxxxxx> > > > --- > > > net/bluetooth/sco.c | 6 ++++-- > > > 1 files changed, 4 insertions(+), 2 deletions(-) > > > > > > diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c > > > index 531a93d..190f70c 100644 > > > --- a/net/bluetooth/sco.c > > > +++ b/net/bluetooth/sco.c > > > @@ -355,8 +355,10 @@ static void __sco_sock_close(struct sock *sk) > > > if (sco_pi(sk)->conn) { > > > sk->sk_state = BT_DISCONN; > > > sco_sock_set_timer(sk, SCO_DISCONN_TIMEOUT); > > > - hci_conn_put(sco_pi(sk)->conn->hcon); > > > - sco_pi(sk)->conn->hcon = NULL; > > > + if (sco_pi(sk)->conn->hcon) { > > > + hci_conn_put(sco_pi(sk)->conn->hcon); > > > + sco_pi(sk)->conn->hcon = NULL; > > > + } > > > } else > > > sco_chan_del(sk, ECONNRESET); > > > break; > > > > Please check if the following patch fixes the issue for you: > > > > commit ae5668c1fc155d3034d0eedcdb52798390975a39 (HEAD, master) > > Author: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx> > > Date: Thu Jan 3 19:59:28 2013 -0200 > > > > Bluetooth: Check if the hci connection exists in SCO shutdown > > > > Checking only for sco_conn seems to not be enough and lead to NULL > > dereferences in the code, check for hcon instead. > > > > <1>[11340.226404] BUG: unable to handle kernel NULL pointer > > dereference at > > 0000000 > > 8 > > <4>[11340.226619] EIP is at __sco_sock_close+0xe8/0x1a0 > > <4>[11340.226629] EAX: f063a740 EBX: 00000000 ECX: f58f4544 EDX: > > 00000000 > > <4>[11340.226640] ESI: dec83e00 EDI: 5f9a081f EBP: e0fdff38 ESP: > > e0fdff1c > > <0>[11340.226674] Stack: > > <4>[11340.226682] c184db87 c1251028 dec83e00 e0fdff38 c1754aef > > dec83e00 > > 00000000 > > e0fdff5c > > <4>[11340.226718] c184f587 e0fdff64 e0fdff68 5f9a081f e0fdff5c > > c1751852 > > d7813800 > > 62262f10 > > <4>[11340.226752] e0fdff70 c1753c00 00000000 00000001 0000000d > > e0fdffac > > c175425c > > 00000041 > > <0>[11340.226793] Call Trace: > > <4>[11340.226813] [<c184db87>] ? sco_sock_clear_timer+0x27/0x60 > > <4>[11340.226831] [<c1251028>] ? local_bh_enable+0x68/0xd0 > > <4>[11340.226846] [<c1754aef>] ? lock_sock_nested+0x4f/0x60 > > <4>[11340.226862] [<c184f587>] sco_sock_shutdown+0x67/0xb0 > > <4>[11340.226879] [<c1751852>] ? sockfd_lookup_light+0x22/0x80 > > <4>[11340.226897] [<c1753c00>] sys_shutdown+0x30/0x60 > > <4>[11340.226912] [<c175425c>] sys_socketcall+0x1dc/0x2a0 > > <4>[11340.226929] [<c149ba78>] ? trace_hardirqs_on_thunk+0xc/0x10 > > <4>[11340.226944] [<c18860f1>] syscall_call+0x7/0xb > > <4>[11340.226960] [<c1880000>] ? restore_cur+0x5e/0xd7 > > <0>[11340.226969] Code: <f0> ff 4b 08 0f 94 c0 84 c0 74 20 80 7b 19 01 74 > > 2f b8 0a 00 00 > > > > Reported-by: Chuansheng Liu <chuansheng.liu@xxxxxxxxx> > > Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx> > > > > diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c > > index 531a93d..57f250c 100644 > > --- a/net/bluetooth/sco.c > > +++ b/net/bluetooth/sco.c > > @@ -352,7 +352,7 @@ static void __sco_sock_close(struct sock *sk) > > > > case BT_CONNECTED: > > case BT_CONFIG: > > - if (sco_pi(sk)->conn) { > > + if (sco_pi(sk)->conn->hcon) { > Your fix is incomplete, at least it should be: > if ( (sco_pi(sk)->conn) && (sco_pi(sk)->conn->hcon)) { > Otherwise, it will bring another crash case. So could you add signed-off-by me also? Can you point any code flow that can crash with my patch? Otherwise I'm just pushing this patch. I don't think we need to check for sco_pi(sk)->conn here. Gustavo -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
