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Fri, 16 Oct 2020 03:15:35 +0000 Received: from BY5PR11MB4241.namprd11.prod.outlook.com ([fe80::3581:4d13:b613:eb81]) by BY5PR11MB4241.namprd11.prod.outlook.com ([fe80::3581:4d13:b613:eb81%7]) with mapi id 15.20.3455.035; Fri, 16 Oct 2020 03:15:35 +0000 Subject: Re: [PATCH] Bluetooth: Use lock_sock() when acquiring lock in sco_conn_del To: Hillf Danton Cc: marcel@holtmann.org, johan.hedberg@gmail.com, davem@davemloft.net, kuba@kernel.org, linux-bluetooth@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20201014071731.34279-1-yanfei.xu@windriver.com> <20201014123113.21888-1-hdanton@sina.com> From: "Xu, Yanfei" Message-ID: <02d6c3a0-401f-46be-bd18-6cf83e9f7c42@windriver.com> Date: Fri, 16 Oct 2020 11:15:27 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 In-Reply-To: <20201014123113.21888-1-hdanton@sina.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [60.247.85.82] X-ClientProxiedBy: YT1PR01CA0123.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:2c::32) To BY5PR11MB4241.namprd11.prod.outlook.com (2603:10b6:a03:1ca::13) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [128.224.162.160] (60.247.85.82) by YT1PR01CA0123.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:2c::32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3477.21 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData: 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 X-OriginatorOrg: windriver.com X-MS-Exchange-CrossTenant-Network-Message-Id: 399fbfe2-504b-40c5-4371-08d87181bf5f X-MS-Exchange-CrossTenant-AuthSource: BY5PR11MB4241.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Oct 2020 03:15:35.1874 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 8ddb2873-a1ad-4a18-ae4e-4644631433be X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 6xSDCcNuw3VhtBueyHbAdPA2bSPykwym18pnN7q9Z5KmH6TMqM/nJcAImFq2yecRjOeP5kltG8XqCNVVWTJMbQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR11MB4974 Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org On 10/14/20 8:31 PM, Hillf Danton wrote: > > On Wed, 14 Oct 2020 15:17:31 +0800 >> From: Yanfei Xu >> >> Locking slock-AF_BLUETOOTH-BTPROTO_SCO may happen in process context or >> BH context. If in process context, we should use lock_sock(). As blow >> warning, sco_conn_del() is called in process context, so let's use >> lock_sock() instead of bh_lock_sock(). >> > Sounds opposite because blocking BH in BH context provides no extra > protection while it makes sense in the less critical context particularly > wrt sock lock. > >> ================================ >> WARNING: inconsistent lock state >> 5.9.0-rc4-syzkaller #0 Not tainted >> -------------------------------- >> inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage. >> syz-executor675/31233 [HC0[0]:SC0[0]:HE1:SE1] takes: >> ffff8880a75c50a0 (slock-AF_BLUETOOTH-BTPROTO_SCO){+.?.}-{2:2}, at: >> spin_lock include/linux/spinlock.h:354 [inline] >> ffff8880a75c50a0 (slock-AF_BLUETOOTH-BTPROTO_SCO){+.?.}-{2:2}, at: >> sco_conn_del+0x128/0x270 net/bluetooth/sco.c:176 >> {IN-SOFTIRQ-W} state was registered at: >> lock_acquire+0x1f3/0xae0 kernel/locking/lockdep.c:5006 >> __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] >> _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 >> spin_lock include/linux/spinlock.h:354 [inline] >> sco_sock_timeout+0x24/0x140 net/bluetooth/sco.c:83 >> call_timer_fn+0x1ac/0x760 kernel/time/timer.c:1413 >> expire_timers kernel/time/timer.c:1458 [inline] >> __run_timers.part.0+0x67c/0xaa0 kernel/time/timer.c:1755 >> __run_timers kernel/time/timer.c:1736 [inline] >> run_timer_softirq+0xae/0x1a0 kernel/time/timer.c:1768 >> __do_softirq+0x1f7/0xa91 kernel/softirq.c:298 >> asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706 >> __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline] >> run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline] >> do_softirq_own_stack+0x9d/0xd0 arch/x86/kernel/irq_64.c:77 >> invoke_softirq kernel/softirq.c:393 [inline] >> __irq_exit_rcu kernel/softirq.c:423 [inline] >> irq_exit_rcu+0x235/0x280 kernel/softirq.c:435 >> sysvec_apic_timer_interrupt+0x51/0xf0 arch/x86/kernel/apic/apic.c:1091 >> asm_sysvec_apic_timer_interrupt+0x12/0x20 >> arch/x86/include/asm/idtentry.h:581 >> unwind_next_frame+0x139a/0x1f90 arch/x86/kernel/unwind_orc.c:607 >> arch_stack_walk+0x81/0xf0 arch/x86/kernel/stacktrace.c:25 >> stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:123 >> kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 >> kasan_set_track mm/kasan/common.c:56 [inline] >> __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461 >> slab_post_alloc_hook mm/slab.h:518 [inline] >> slab_alloc mm/slab.c:3312 [inline] >> kmem_cache_alloc+0x13a/0x3a0 mm/slab.c:3482 >> __d_alloc+0x2a/0x950 fs/dcache.c:1709 >> d_alloc+0x4a/0x230 fs/dcache.c:1788 >> d_alloc_parallel+0xe9/0x18e0 fs/dcache.c:2540 >> lookup_open.isra.0+0x9ac/0x1350 fs/namei.c:3030 >> open_last_lookups fs/namei.c:3177 [inline] >> path_openat+0x96d/0x2730 fs/namei.c:3365 >> do_filp_open+0x17e/0x3c0 fs/namei.c:3395 >> do_sys_openat2+0x16d/0x420 fs/open.c:1168 >> do_sys_open fs/open.c:1184 [inline] >> __do_sys_open fs/open.c:1192 [inline] >> __se_sys_open fs/open.c:1188 [inline] >> __x64_sys_open+0x119/0x1c0 fs/open.c:1188 >> do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 >> entry_SYSCALL_64_after_hwframe+0x44/0xa9 >> irq event stamp: 853 >> hardirqs last enabled at (853): [] >> __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline] >> hardirqs last enabled at (853): [] >> _raw_spin_unlock_irq+0x1f/0x80 kernel/locking/spinlock.c:199 >> hardirqs last disabled at (852): [] >> __raw_spin_lock_irq include/linux/spinlock_api_smp.h:126 [inline] >> hardirqs last disabled at (852): [] >> _raw_spin_lock_irq+0xa4/0xd0 kernel/locking/spinlock.c:167 >> softirqs last enabled at (0): [] >> copy_process+0x1a99/0x6920 kernel/fork.c:2018 >> softirqs last disabled at (0): [<0000000000000000>] 0x0 >> >> other info that might help us debug this: >> Possible unsafe locking scenario: >> >> CPU0 >> ---- >> lock(slock-AF_BLUETOOTH-BTPROTO_SCO); >> >> lock(slock-AF_BLUETOOTH-BTPROTO_SCO); >> >> *** DEADLOCK *** >> >> 3 locks held by syz-executor675/31233: >> #0: ffff88809f104f40 (&hdev->req_lock){+.+.}-{3:3}, at: >> hci_dev_do_close+0xf5/0x1080 net/bluetooth/hci_core.c:1720 >> #1: ffff88809f104078 (&hdev->lock){+.+.}-{3:3}, at: >> hci_dev_do_close+0x253/0x1080 net/bluetooth/hci_core.c:1757 >> #2: ffffffff8a9188c8 (hci_cb_list_lock){+.+.}-{3:3}, at: >> hci_disconn_cfm include/net/bluetooth/hci_core.h:1435 [inline] >> #2: ffffffff8a9188c8 (hci_cb_list_lock){+.+.}-{3:3}, at: >> hci_conn_hash_flush+0xc7/0x220 net/bluetooth/hci_conn.c:1557 >> >> stack backtrace: >> CPU: 1 PID: 31233 Comm: syz-executor675 Not tainted 5.9.0-rc4-syzkaller >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS >> Google 01/01/2011 >> Call Trace: >> __dump_stack lib/dump_stack.c:77 [inline] >> dump_stack+0x198/0x1fd lib/dump_stack.c:118 >> print_usage_bug kernel/locking/lockdep.c:4020 [inline] >> valid_state kernel/locking/lockdep.c:3361 [inline] >> mark_lock_irq kernel/locking/lockdep.c:3560 [inline] >> mark_lock.cold+0x7a/0x7f kernel/locking/lockdep.c:4006 >> mark_usage kernel/locking/lockdep.c:3923 [inline] >> __lock_acquire+0x876/0x5570 kernel/locking/lockdep.c:4380 >> lock_acquire+0x1f3/0xae0 kernel/locking/lockdep.c:5006 >> __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] >> _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 >> spin_lock include/linux/spinlock.h:354 [inline] >> sco_conn_del+0x128/0x270 net/bluetooth/sco.c:176 >> sco_disconn_cfm net/bluetooth/sco.c:1178 [inline] >> sco_disconn_cfm+0x62/0x80 net/bluetooth/sco.c:1171 >> hci_disconn_cfm include/net/bluetooth/hci_core.h:1438 [inline] >> hci_conn_hash_flush+0x114/0x220 net/bluetooth/hci_conn.c:1557 >> hci_dev_do_close+0x5c6/0x1080 net/bluetooth/hci_core.c:1770 >> hci_unregister_dev+0x1bd/0xe30 net/bluetooth/hci_core.c:3790 >> vhci_release+0x70/0xe0 drivers/bluetooth/hci_vhci.c:340 >> __f put+0x285/0x920 fs/file_table.c:281 >> task_work_run+0xdd/0x190 kernel/task_work.c:141 >> exit_task_work include/linux/task_work.h:25 [inline] >> do_exit+0xb7d/0x29f0 kernel/exit.c:806 >> do_group_exit+0x125/0x310 kernel/exit.c:903 >> get_signal+0x428/0x1f00 kernel/signal.c:2757 >> arch_do_signal+0x82/0x2520 arch/x86/kernel/signal.c:811 >> exit_to_user_mode_loop kernel/entry/common.c:159 [inline] >> exit_to_user_mode_prepare+0x1ae/0x200 kernel/entry/common.c:190 >> syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:265 >> entry_SYSCALL_64_after_hwframe+0x44/0xa9 >> RIP: 0033:0x447279 >> >> Reported-by: syzbot+65684128cd7c35bc66a1@syzkaller.appspotmail.com >> Signed-off-by: Yanfei Xu >> --- >> net/bluetooth/sco.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c >> index dcf7f96ff417..559b883c815f 100644 >> --- a/net/bluetooth/sco.c >> +++ b/net/bluetooth/sco.c >> @@ -173,10 +173,10 @@ static void sco_conn_del(struct hci_conn *hcon, int err) >> >> if (sk) { >> sock_hold(sk); >> - bh_lock_sock(sk); >> + lock_sock(sk); >> sco_sock_clear_timer(sk); >> sco_chan_del(sk, err); >> - bh_unlock_sock(sk); >> + release_sock(sk); >> sco_sock_kill(sk); >> sock_put(sk); >> } >> -- >> 2.18.2 > > > --- a/net/bluetooth/sco.c > +++ b/net/bluetooth/sco.c > @@ -80,10 +80,10 @@ static void sco_sock_timeout(struct time > > BT_DBG("sock %p state %d", sk, sk->sk_state); > > - bh_lock_sock(sk); > + lock_sock(sk); > sk->sk_err = ETIMEDOUT; > sk->sk_state_change(sk); > - bh_unlock_sock(sk); > + unlock_sock(sk); > > sco_sock_kill(sk); > sock_put(sk); > Hi Hillf, Thanks for your reply! But I don't clearly understand what you mean. After your change, If sco_conn_del（） have got the lock and then run into sco_sock_timeout which is in BH, the potential deadlock is still exsit. As the function define, use bh_lock_sock in sco_sock_timeout(BH context) is right. The root cause is prevent from locking in BH after we've got the lock in sco_conn_del, isn't it? /* BH context may only use the following locking interface. */ #define bh_lock_sock(__sk) spin_lock(&((__sk)->sk_lock.slock)) Regards, Yanfei