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[71.59.129.171]) by smtp.gmail.com with ESMTPSA id z14-20020aa791ce000000b00571cdbd0771sm333790pfa.102.2023.03.30.15.03.35 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Mar 2023 15:03:35 -0700 (PDT) From: Luiz Augusto von Dentz To: linux-bluetooth@vger.kernel.org Subject: [PATCH 2/2] Bluetooth: SCO: Fix possible circular locking dependency sco_sock_getsockopt Date: Thu, 30 Mar 2023 15:03:32 -0700 Message-Id: <20230330220332.1035910-3-luiz.dentz@gmail.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230330220332.1035910-1-luiz.dentz@gmail.com> References: <20230330220332.1035910-1-luiz.dentz@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org From: Luiz Augusto von Dentz This attempts to fix the following trace: ====================================================== WARNING: possible circular locking dependency detected 6.3.0-rc2-g68fcb3a7bf97 #4706 Not tainted ------------------------------------------------------ sco-tester/31 is trying to acquire lock: ffff8880025b8070 (&hdev->lock){+.+.}-{3:3}, at: sco_sock_getsockopt+0x1fc/0xa90 but task is already holding lock: ffff888001eeb130 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_sock_getsockopt+0x104/0xa90 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}: lock_sock_nested+0x32/0x80 sco_connect_cfm+0x118/0x4a0 hci_sync_conn_complete_evt+0x1e6/0x3d0 hci_event_packet+0x55c/0x7c0 hci_rx_work+0x34c/0xa00 process_one_work+0x575/0x910 worker_thread+0x89/0x6f0 kthread+0x14e/0x180 ret_from_fork+0x2b/0x50 -> #1 (hci_cb_list_lock){+.+.}-{3:3}: __mutex_lock+0x13b/0xcc0 hci_sync_conn_complete_evt+0x1ad/0x3d0 hci_event_packet+0x55c/0x7c0 hci_rx_work+0x34c/0xa00 process_one_work+0x575/0x910 worker_thread+0x89/0x6f0 kthread+0x14e/0x180 ret_from_fork+0x2b/0x50 -> #0 (&hdev->lock){+.+.}-{3:3}: __lock_acquire+0x18cc/0x3740 lock_acquire+0x151/0x3a0 __mutex_lock+0x13b/0xcc0 sco_sock_getsockopt+0x1fc/0xa90 __sys_getsockopt+0xe9/0x190 __x64_sys_getsockopt+0x5b/0x70 do_syscall_64+0x42/0x90 entry_SYSCALL_64_after_hwframe+0x70/0xda other info that might help us debug this: Chain exists of: &hdev->lock --> hci_cb_list_lock --> sk_lock-AF_BLUETOOTH-BTPROTO_SCO Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sk_lock-AF_BLUETOOTH-BTPROTO_SCO); lock(hci_cb_list_lock); lock(sk_lock-AF_BLUETOOTH-BTPROTO_SCO); lock(&hdev->lock); *** DEADLOCK *** 1 lock held by sco-tester/31: #0: ffff888001eeb130 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_sock_getsockopt+0x104/0xa90 Fixes: 248733e87d50 ("Bluetooth: Allow querying of supported offload codecs over SCO socket") Signed-off-by: Luiz Augusto von Dentz --- net/bluetooth/sco.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c index f3a5ab9e4fa4..cd1a27ac555d 100644 --- a/net/bluetooth/sco.c +++ b/net/bluetooth/sco.c @@ -1140,6 +1140,8 @@ static int sco_sock_getsockopt(struct socket *sock, int level, int optname, break; } + release_sock(sk); + /* find total buffer size required to copy codec + caps */ hci_dev_lock(hdev); list_for_each_entry(c, &hdev->local_codecs, list) { @@ -1157,15 +1159,13 @@ static int sco_sock_getsockopt(struct socket *sock, int level, int optname, buf_len += sizeof(struct bt_codecs); if (buf_len > len) { hci_dev_put(hdev); - err = -ENOBUFS; - break; + return -ENOBUFS; } ptr = optval; if (put_user(num_codecs, ptr)) { hci_dev_put(hdev); - err = -EFAULT; - break; + return -EFAULT; } ptr += sizeof(num_codecs); @@ -1205,12 +1205,14 @@ static int sco_sock_getsockopt(struct socket *sock, int level, int optname, ptr += len; } - if (!err && put_user(buf_len, optlen)) - err = -EFAULT; - hci_dev_unlock(hdev); hci_dev_put(hdev); + lock_sock(sk); + + if (!err && put_user(buf_len, optlen)) + err = -EFAULT; + break; default: