Return-Path: From: Johan Hovold To: Marcel Holtmann , "Gustavo F. Padovan" Cc: "David S. Miller" , linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, David Herrmann , Greg KH , Johan Hovold , stable Subject: [PATCH 2/2] bluetooth: hci_core: fix NULL-pointer dereference at unregister Date: Thu, 15 Mar 2012 14:48:41 +0100 Message-Id: <1331819321-13018-2-git-send-email-jhovold@gmail.com> In-Reply-To: <1331819321-13018-1-git-send-email-jhovold@gmail.com> References: <20120315134735.GA19821@localhost> <1331819321-13018-1-git-send-email-jhovold@gmail.com> List-ID: Make sure hci_dev_open returns immediately if hci_dev_unregister has been called. This fixes a race between hci_dev_open and hci_dev_unregister which can lead to a NULL-pointer dereference. Bug is 100% reproducible using hciattach and a disconnected serial port: 0. # hciattach -n /dev/ttyO1 any noflow 1. hci_dev_open called from hci_power_on grabs req lock 2. hci_init_req executes but device fails to initialise (times out eventually) 3. hci_dev_open is called from hci_sock_ioctl and sleeps on req lock 4. hci_uart_tty_close calls hci_dev_unregister and sleeps on req lock in hci_dev_do_close 5. hci_dev_open (1) releases req lock 6. hci_dev_do_close grabs req lock and returns as device is not up 7. hci_dev_unregister sleeps in destroy_workqueue 8. hci_dev_open (3) grabs req lock, calls hci_init_req and eventually sleeps 9. hci_dev_unregister finishes, while hci_dev_open is still running... [ 79.627136] INFO: trying to register non-static key. [ 79.632354] the code is fine but needs lockdep annotation. [ 79.638122] turning off the locking correctness validator. [ 79.643920] [] (unwind_backtrace+0x0/0xf8) from [] (__lock_acquire+0x1590/0x1ab0) [ 79.653594] [] (__lock_acquire+0x1590/0x1ab0) from [] (lock_acquire+0x9c/0x128) [ 79.663085] [] (lock_acquire+0x9c/0x128) from [] (run_timer_softirq+0x150/0x3ac) [ 79.672668] [] (run_timer_softirq+0x150/0x3ac) from [] (__do_softirq+0xd4/0x22c) [ 79.682281] [] (__do_softirq+0xd4/0x22c) from [] (irq_exit+0x8c/0x94) [ 79.690856] [] (irq_exit+0x8c/0x94) from [] (handle_IRQ+0x34/0x84) [ 79.699157] [] (handle_IRQ+0x34/0x84) from [] (omap3_intc_handle_irq+0x48/0x4c) [ 79.708648] [] (omap3_intc_handle_irq+0x48/0x4c) from [] (__irq_usr+0x3c/0x60) [ 79.718048] Exception stack(0xcf281fb0 to 0xcf281ff8) [ 79.723358] 1fa0: 0001e6a0 be8dab00 0001e698 00036698 [ 79.731933] 1fc0: 0002df98 0002df38 0000001f 00000000 b6f234d0 00000000 00000004 00000000 [ 79.740509] 1fe0: 0001e6f8 be8d6aa0 be8dac50 0000aab8 80000010 ffffffff [ 79.747497] Unable to handle kernel NULL pointer dereference at virtual address 00000000 [ 79.756011] pgd = cf3b4000 [ 79.758850] [00000000] *pgd=8f0c7831, *pte=00000000, *ppte=00000000 [ 79.765502] Internal error: Oops: 80000007 [#1] [ 79.770294] Modules linked in: [ 79.773529] CPU: 0 Tainted: G W (3.3.0-rc6-00002-gb5d5c87 #421) [ 79.781066] PC is at 0x0 [ 79.783721] LR is at run_timer_softirq+0x16c/0x3ac [ 79.788787] pc : [<00000000>] lr : [] psr: 60000113 [ 79.788787] sp : cf281ee0 ip : 00000000 fp : cf280000 [ 79.800903] r10: 00000004 r9 : 00000100 r8 : b6f234d0 [ 79.806427] r7 : c0519c28 r6 : cf093488 r5 : c0561a00 r4 : 00000000 [ 79.813323] r3 : 00000000 r2 : c054eee0 r1 : 00000001 r0 : 00000000 [ 79.820190] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user [ 79.827728] Control: 10c5387d Table: 8f3b4019 DAC: 00000015 [ 79.833801] Process gpsd (pid: 1265, stack limit = 0xcf2802e8) [ 79.839965] Stack: (0xcf281ee0 to 0xcf282000) [ 79.844573] 1ee0: 00000002 00000000 c0040a24 00000000 00000002 cf281f08 00200200 00000000 [ 79.853210] 1f00: 00000000 cf281f18 cf281f08 00000000 00000000 00000000 cf281f18 cf281f18 [ 79.861816] 1f20: 00000000 00000001 c056184c 00000000 00000001 b6f234d0 c0561848 00000004 [ 79.870452] 1f40: cf280000 c003a3b8 c051e79c 00000001 00000000 00000100 3fa9e7b8 0000000a [ 79.879089] 1f60: 00000025 cf280000 00000025 00000000 00000000 b6f234d0 00000000 00000004 [ 79.887756] 1f80: 00000000 c003a924 c053ad38 c0013a50 fa200000 cf281fb0 ffffffff c0008530 [ 79.896362] 1fa0: 0001e6a0 0000aab8 80000010 c037499c 0001e6a0 be8dab00 0001e698 00036698 [ 79.904998] 1fc0: 0002df98 0002df38 0000001f 00000000 b6f234d0 00000000 00000004 00000000 [ 79.913665] 1fe0: 0001e6f8 be8d6aa0 be8dac50 0000aab8 80000010 ffffffff 00fbf700 04ffff00 [ 79.922302] [] (run_timer_softirq+0x16c/0x3ac) from [] (__do_softirq+0xd4/0x22c) [ 79.931945] [] (__do_softirq+0xd4/0x22c) from [] (irq_exit+0x8c/0x94) [ 79.940582] [] (irq_exit+0x8c/0x94) from [] (handle_IRQ+0x34/0x84) [ 79.948913] [] (handle_IRQ+0x34/0x84) from [] (omap3_intc_handle_irq+0x48/0x4c) [ 79.958404] [] (omap3_intc_handle_irq+0x48/0x4c) from [] (__irq_usr+0x3c/0x60) [ 79.967773] Exception stack(0xcf281fb0 to 0xcf281ff8) [ 79.973083] 1fa0: 0001e6a0 be8dab00 0001e698 00036698 [ 79.981658] 1fc0: 0002df98 0002df38 0000001f 00000000 b6f234d0 00000000 00000004 00000000 [ 79.990234] 1fe0: 0001e6f8 be8d6aa0 be8dac50 0000aab8 80000010 ffffffff [ 79.997161] Code: bad PC value [ 80.000396] ---[ end trace 6f6739840475f9ee ]--- [ 80.005279] Kernel panic - not syncing: Fatal exception in interrupt Cc: stable Signed-off-by: Johan Hovold --- include/net/bluetooth/hci.h | 1 + net/bluetooth/hci_core.c | 7 +++++++ 2 files changed, 8 insertions(+), 0 deletions(-) diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h index 344b0f9..8f928f7 100644 --- a/include/net/bluetooth/hci.h +++ b/include/net/bluetooth/hci.h @@ -92,6 +92,7 @@ enum { HCI_SERVICE_CACHE, HCI_LINK_KEYS, HCI_DEBUG_KEYS, + HCI_UNREGISTER, HCI_LE_SCAN, HCI_SSP_ENABLED, diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c index 2f3e1bb..2e3f193 100644 --- a/net/bluetooth/hci_core.c +++ b/net/bluetooth/hci_core.c @@ -666,6 +666,11 @@ int hci_dev_open(__u16 dev) hci_req_lock(hdev); + if (test_bit(HCI_UNREGISTER, &hdev->dev_flags)) { + ret = -ENODEV; + goto done; + } + if (hdev->rfkill && rfkill_blocked(hdev->rfkill)) { ret = -ERFKILL; goto done; @@ -1850,6 +1855,8 @@ void hci_unregister_dev(struct hci_dev *hdev) BT_DBG("%p name %s bus %d", hdev, hdev->name, hdev->bus); + set_bit(HCI_UNREGISTER, &hdev->dev_flags); + write_lock(&hci_dev_list_lock); list_del(&hdev->list); write_unlock(&hci_dev_list_lock); -- 1.7.8.4