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Mon, 19 Oct 2020 01:54:10 +0000 Received: from BY5PR11MB4241.namprd11.prod.outlook.com ([fe80::adbd:559a:4a78:f09b]) by BY5PR11MB4241.namprd11.prod.outlook.com ([fe80::adbd:559a:4a78:f09b%6]) with mapi id 15.20.3477.028; Mon, 19 Oct 2020 01:54:10 +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> <20201016041028.601-1-hdanton@sina.com> From: "Xu, Yanfei" Message-ID: <66fa69e5-a184-7924-229b-0dd7067989ee@windriver.com> Date: Mon, 19 Oct 2020 09:54:01 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 In-Reply-To: <20201016041028.601-1-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: HK2PR02CA0205.apcprd02.prod.outlook.com (2603:1096:201:20::17) 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 HK2PR02CA0205.apcprd02.prod.outlook.com (2603:1096:201:20::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3477.20 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: 2b00a232-86f3-48c8-e845-08d873d1df56 X-MS-Exchange-CrossTenant-AuthSource: BY5PR11MB4241.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Oct 2020 01:54:10.7557 (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: EKcODLnNOHz6gVBaKo9dVjAPVEEHGfv6we2jADAgK4SGwKfrFWcJQLKN5d5BZWDxszlLoMFDuGrEOgDVqgAIPA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR11MB2904 Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org On 10/16/20 12:10 PM, Hillf Danton wrote: > On Fri, 16 Oct 2020 11:15:27 +0800 Yanfei Xu wrote: >> 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. > > My change is incorrect. Thanks for your reply. > >> >> 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)) > > Then replacing bh_lock_sock() with lock_sock() in sco_conn_del() seems > not to work because bh is enabled after lock_sock(). What we want instead > is block bh here until we release sock, something like the diff below. > > --- a/net/bluetooth/sco.c > +++ b/net/bluetooth/sco.c > @@ -173,10 +173,12 @@ static void sco_conn_del(struct hci_conn > > if (sk) { > sock_hold(sk); > + local_bh_disable(); > bh_lock_sock(sk); > sco_sock_clear_timer(sk); > sco_chan_del(sk, err); > bh_unlock_sock(sk); > + local_bh_enable(); > sco_sock_kill(sk); > sock_put(sk); > } > Anyone else have any suggestion? :) Thanks, Yanfei