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Date: Tue, 7 Oct 2014 18:16:31 +0200
Message-ID: <CANq1E4RUQnW1qKszt8wJ+xBadHrCjo=J-POL79SbMRAj8v=wjQ@mail.gmail.com>
Subject: Re: 3.17-rc5: kernel oops when exiting X under heavy load
From: David Herrmann <dh.herrmann@gmail.com>
To: Dmitry Torokhov <dtor@mail.ru>
Cc: Pavel Machek <pavel@ucw.cz>, kernel list <linux-kernel@vger.kernel.org>,
        "open list:HID CORE LAYER" <linux-input@vger.kernel.org>
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Hi

On Mon, Oct 6, 2014 at 8:12 PM, Dmitry Torokhov <dtor@mail.ru> wrote:
> On Sat, Oct 04, 2014 at 01:11:10AM +0200, Pavel Machek wrote:
>> Hi!
>>
>> From the backtrace, it looks evdev related...?
>
> Hmm, looks like it...
>
>>
>>
>> Oct  4 00:59:47 duo wpa_supplicant[3824]: wlan0: SME: Trying to authenticate with 00:11:95:05:30:d7 (SSID='pavel' freq=2412 MHz)
>> Oct  4 00:59:47 duo wpa_supplicant[3824]: wlan0: Trying to associate with 00:11:95:05:30:d7 (SSID='pavel' freq=2412 MHz)
>> Oct  4 00:59:47 duo NetworkManager[3465]: <info> (wlan0): supplicant interface state: scanning -> authenticating
>> Oct  4 00:59:47 duo wpa_supplicant[3824]: wlan0: Associated with 00:11:95:05:30:d7
>> Oct  4 00:59:47 duo wpa_supplicant[3824]: wlan0: CTRL-EVENT-CONNECTED - Connection to 00:11:95:05:30:d7 completed (reauth) [id=0 id_str=]
>> Oct  4 00:59:47 duo NetworkManager[3465]: <info> (wlan0): supplicant interface state: authenticating -> associating
>> Oct  4 00:59:47 duo NetworkManager[3465]: <info> (wlan0): supplicant interface state: associating -> completed
>> Oct  4 00:59:55 duo kernel: BUG: unable to handle kernel paging request at f47b5000
>> Oct  4 00:59:55 duo kernel: IP: [<c42765ff>] memcpy+0xf/0x20
>> Oct  4 00:59:55 duo kernel: *pde = 373f3067 *pte = 347b5060
>> Oct  4 00:59:55 duo kernel: Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
>> Oct  4 00:59:55 duo kernel: Modules linked in:
>> Oct  4 00:59:55 duo kernel: CPU: 0 PID: 22293 Comm: Xorg Not tainted 3.17.0-rc5+ #399
>> Oct  4 00:59:55 duo kernel: Hardware name: LENOVO 17097HU/17097HU, BIOS 7BETD8WW (2.19 ) 03/31/2011
>> Oct  4 00:59:55 duo kernel: task: eb4b1580 ti: ec6a2000 task.ti: ec6a2000
>> Oct  4 00:59:55 duo kernel: EIP: 0060:[<c42765ff>] EFLAGS: 00213006 CPU: 0
>> Oct  4 00:59:55 duo kernel: EIP is at memcpy+0xf/0x20
>> Oct  4 00:59:55 duo kernel: EAX: f5c42000 EBX: 00000bfc ECX: 00000146 EDX: f47b491c
>> Oct  4 00:59:55 duo kernel: ESI: f47b5000 EDI: f5c426e4 EBP: ec6a3e80 ESP: ec6a3e74
>> Oct  4 00:59:55 duo kernel: DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
>> Oct  4 00:59:55 duo kernel: CR0: 80050033 CR2: f47b5000 CR3: 2c77d000 CR4: 00000710
>> Oct  4 00:59:55 duo kernel: Stack:
>> Oct  4 00:59:55 duo kernel: ec409800 f47b499c 00000bfc ec6a3ec4 c451f154 ec40980c f5c42000 c47ee121
>> Oct  4 00:59:55 duo kernel: 00000001 00000001 00000000 00203246 c47ef168 c451f367 f47cdcb4 eb4b1580
>> Oct  4 00:59:55 duo kernel: 00203246 eab3eec0 ec409800 ec409800 ec6a3f2c c451f468 f47b491c 000002ff
>> Oct  4 00:59:55 duo kernel: Call Trace:
>> Oct  4 00:59:55 duo kernel: [<c451f154>] evdev_handle_get_val.isra.7+0x54/0x240
>> Oct  4 00:59:55 duo kernel: [<c47ee121>] ? mutex_lock_interruptible_nested+0x31/0x330
>> Oct  4 00:59:55 duo kernel: [<c47ef168>] ? mutex_unlock+0x8/0x10
>> Oct  4 00:59:55 duo kernel: [<c451f367>] ? evdev_ioctl+0x27/0x7f0
>> Oct  4 00:59:55 duo kernel: [<c451f468>] evdev_ioctl+0x128/0x7f0
>> Oct  4 00:59:55 duo kernel: [<c40e9c5c>] ? cache_free_debugcheck+0x2ac/0x340
>> Oct  4 00:59:55 duo kernel: [<c451f340>] ? evdev_handle_get_val.isra.7+0x240/0x240
>> Oct  4 00:59:55 duo kernel: [<c40fead2>] do_vfs_ioctl+0x2f2/0x520
>> Oct  4 00:59:55 duo kernel: [<c40f8178>] ? final_putname+0x18/0x40
>> Oct  4 00:59:55 duo kernel: [<c40f8178>] ? final_putname+0x18/0x40
>> Oct  4 00:59:55 duo kernel: [<c40ee12a>] ? do_sys_open+0x17a/0x200
>> Oct  4 00:59:55 duo kernel: [<c40fed36>] SyS_ioctl+0x36/0x70
>> Oct  4 00:59:55 duo kernel: [<c47f105e>] syscall_call+0x7/0x7
>> Oct  4 00:59:55 duo kernel: [<c47f0000>] ? hrtimer_nanosleep_restart+0x60/0xa0
>> Oct  4 00:59:55 duo kernel: Code: fb ff ff 8b 43 54 2b 43 50 88 43 4e 5b 5d f3 c3 90 90 90 90 90 90 90 90 90 90 90 90 55 89 e5 57 89 c7 56 89 d6 53 89 cb c1 e9 02 <f3> a5 89 d9 83 e1 03 74 02 f3 a4 5b 5e 5f 5d c3 90 55 89 e5 57
>> Oct  4 00:59:55 duo kernel: EIP: [<c42765ff>] memcpy+0xf/0x20 SS:ESP 0068:ec6a3e74
>> Oct  4 00:59:55 duo kernel: CR2: 00000000f47b5000
>> Oct  4 00:59:55 duo kernel: ---[ end trace fee349319591dc44 ]---
>> Oct  4 01:04:08 duo rsyslogd: [origin software="rsyslogd" swVersion="8.4.0" x-pid="3490" x-info="http://www.rsyslog.com"] start
>>
>
> Does the patch below help by any chance?
>
> Thanks.
>
> --
> Dmitry
>
>
> Input: evdev - fix EVIOCG{type} ioctl
>
> From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
>
> The 'max' size passed into the function is measured in number of bits
> (KEY_MAX, LED_MAX, etc) so we nedd to convert it accoidingly before tyring
> to copy the data out, otherwise we will try copying too much and end up
> with up with a page fault.
>
> Reported-by: Pavel Machek <pavel@ucw.cz>
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> ---
>  drivers/input/evdev.c |   13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
> index de05545..bc20348 100644
> --- a/drivers/input/evdev.c
> +++ b/drivers/input/evdev.c
> @@ -738,20 +738,23 @@ static int evdev_handle_set_keycode_v2(struct input_dev *dev, void __user *p)
>   */
>  static int evdev_handle_get_val(struct evdev_client *client,
>                                 struct input_dev *dev, unsigned int type,
> -                               unsigned long *bits, unsigned int max,
> -                               unsigned int size, void __user *p, int compat)
> +                               unsigned long *bits, unsigned int maxbit,
> +                               unsigned int maxlen, void __user *p,
> +                               int compat)
>  {
>         int ret;
>         unsigned long *mem;
> +       size_t len;
>
> -       mem = kmalloc(sizeof(unsigned long) * max, GFP_KERNEL);
> +       len = BITS_TO_LONGS(maxbit) * sizeof(unsigned long);
> +       mem = kmalloc(len, GFP_KERNEL);
>         if (!mem)
>                 return -ENOMEM;
>
>         spin_lock_irq(&dev->event_lock);
>         spin_lock(&client->buffer_lock);
>
> -       memcpy(mem, bits, sizeof(unsigned long) * max);
> +       memcpy(mem, bits, len);

So this is where it breaks? Because we copy from "bits", which is an
array in the input-device? Very unlikely to trigger, I guess. Sure, so
far we overallocate and copy way to much into the array, but the
bits_to_user() truncates it properly. So afaics, this only fails if
the kernel memory isn't accessible, and thus faults.

Patch looks good! Nice catch:

Reviewed-by: David Herrmann <dh.herrmann@gmail.com>

Thanks
David

>
>         spin_unlock(&dev->event_lock);
>
> @@ -759,7 +762,7 @@ static int evdev_handle_get_val(struct evdev_client *client,
>
>         spin_unlock_irq(&client->buffer_lock);
>
> -       ret = bits_to_user(mem, max, size, p, compat);
> +       ret = bits_to_user(mem, maxbit, maxlen, p, compat);
>         if (ret < 0)
>                 evdev_queue_syn_dropped(client);
>