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Message-id: <528BF9DB.6050308@samsung.com>
Date: Tue, 19 Nov 2013 16:52:59 -0700
From: Shuah Khan <shuah.kh@...sung.com>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>,
Greg KH <gregkh@...uxfoundation.org>
Cc: len.brown@...el.com, pavel@....cz, anton@...msg.org,
dwmw2@...radead.org, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org, shuahkhan@...il.com,
Shuah Khan <shuah.kh@...sung.com>
Subject: Re: [PATCH 2/2] power: Change device_wakeup_enable() to WARN_ON on
null dev_name(dev)
On 11/19/2013 04:56 PM, Rafael J. Wysocki wrote:
> On Tuesday, November 19, 2013 03:14:01 PM Greg KH wrote:
>> On Tue, Nov 19, 2013 at 09:05:46AM -0700, Shuah Khan wrote:
>>> device_wakeup_enable() uses dev_name(dev) as the wakeup source name.
>>> When it gets called with a device with its name not yet set, ws structure
>>> with ws->name = NULL gets created.
>>>
>>> When kernel is booted with wakeup_source_activate enabled, it will panic
>>> when the trace point code tries to dereferences ws->name.
>>>
>>> Change device_wakeup_enable() to WARN_ON on dev_name(dev) null condition
>>> to detect driver bugs that result in calling device_wakeup_enable() before
>>> device is fully initialized with its name in device_wakeup_enable().
>>>
>>> This change without the power_supply_register() fix will result in early
>>> boot panics when AC Adapter and Battery device drivers try to register
>>> wakeup source.
>>>
>>> The following panic resulted from power_supply_register() registering
>>> wakeup source with a null device name.
>>>
>>> [ 819.769934] device: 'BAT1': device_add
>>> [ 819.770078] PM: Adding info for No Bus:BAT1
>>> [ 819.770235] BUG: unable to handle kernel NULL pointer dereference at (null)
>>> [ 819.770435] IP: [<ffffffff813381c0>] skip_spaces+0x30/0x30
>>> [ 819.770572] PGD 3efd90067 PUD 3eff61067 PMD 0
>>> [ 819.770716] Oops: 0000 [#1] SMP
>>> [ 819.770829] Modules linked in: arc4 iwldvm mac80211 x86_pkg_temp_thermal coretemp kvm_intel joydev i915 kvm uvcvideo ghash_clmulni_intel videobuf2_vmalloc aesni_intel videobuf2_memops videobuf2_core aes_x86_64 ablk_helper cryptd videodev iwlwifi lrw rfcomm gf128mul glue_helper bnep btusb media bluetooth parport_pc hid_generic ppdev snd_hda_codec_hdmi drm_kms_helper snd_hda_codec_realtek cfg80211 drm tpm_infineon samsung_laptop snd_hda_intel usbhid snd_hda_codec hid snd_hwdep snd_pcm microcode snd_page_alloc snd_timer psmouse i2c_algo_bit lpc_ich tpm_tis video wmi mac_hid serio_raw ext2 lp parport r8169 mii
>>> [ 819.771802] CPU: 0 PID: 2167 Comm: bash Not tainted 3.12.0+ #25
>>> [ 819.771876] Hardware name: SAMSUNG ELECTRONICS CO., LTD. 900X3C/900X3D/900X4C/900X4D/SAMSUNG_NP1234567890, BIOS P03AAC 07/12/2012
>>> [ 819.772022] task: ffff88002e6ddcc0 ti: ffff8804015ca000 task.ti: ffff8804015ca000
>>> [ 819.772119] RIP: 0010:[<ffffffff813381c0>] [<ffffffff813381c0>] skip_spaces+0x30/0x30
>>> [ 819.772242] RSP: 0018:ffff8804015cbc70 EFLAGS: 00010046
>>> [ 819.772310] RAX: 0000000000000003 RBX: ffff88040cfd6d40 RCX: 0000000000000018
>>> [ 819.772397] RDX: 0000000000020001 RSI: 0000000000000000 RDI: 0000000000000000
>>> [ 819.772484] RBP: ffff8804015cbcc0 R08: 0000000000000000 R09: ffff8803f0768d40
>>> [ 819.772570] R10: ffffea001033b800 R11: 0000000000000000 R12: ffffffff81c519c0
>>> [ 819.772656] R13: 0000000000020001 R14: 0000000000000000 R15: 0000000000020001
>>> [ 819.772744] FS: 00007ff98309b740(0000) GS:ffff88041f200000(0000) knlGS:0000000000000000
>>> [ 819.772845] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> [ 819.772917] CR2: 0000000000000000 CR3: 00000003f59dc000 CR4: 00000000001407f0
>>> [ 819.773001] Stack:
>>> [ 819.773030] ffffffff81114003 ffff8804015cbcb0 0000000000000000 0000000000000046
>>> [ 819.773146] ffff880409757a18 ffff8803f065a160 0000000000000000 0000000000020001
>>> [ 819.773273] 0000000000000000 0000000000000000 ffff8804015cbce8 ffffffff8143e388
>>> [ 819.773387] Call Trace:
>>> [ 819.773434] [<ffffffff81114003>] ? ftrace_raw_event_wakeup_source+0x43/0xe0
>>> [ 819.773520] [<ffffffff8143e388>] wakeup_source_report_event+0xb8/0xd0
>>> [ 819.773595] [<ffffffff8143e3cd>] __pm_stay_awake+0x2d/0x50
>>> [ 819.773724] [<ffffffff8153395c>] power_supply_changed+0x3c/0x90
>>> [ 819.773795] [<ffffffff8153407c>] power_supply_register+0x18c/0x250
>>> [ 819.773869] [<ffffffff813d8d18>] sysfs_add_battery+0x61/0x7b
>>> [ 819.773935] [<ffffffff813d8d69>] battery_notify+0x37/0x3f
>>> [ 819.774001] [<ffffffff816ccb7c>] notifier_call_chain+0x4c/0x70
>>> [ 819.774071] [<ffffffff81073ded>] __blocking_notifier_call_chain+0x4d/0x70
>>> [ 819.774149] [<ffffffff81073e26>] blocking_notifier_call_chain+0x16/0x20
>>> [ 819.774227] [<ffffffff8109397a>] pm_notifier_call_chain+0x1a/0x40
>>> [ 819.774316] [<ffffffff81095b66>] hibernate+0x66/0x1c0
>>> [ 819.774407] [<ffffffff81093931>] state_store+0x71/0xa0
>>> [ 819.774507] [<ffffffff81331d8f>] kobj_attr_store+0xf/0x20
>>> [ 819.774613] [<ffffffff811f8618>] sysfs_write_file+0x128/0x1c0
>>> [ 819.774735] [<ffffffff8118579d>] vfs_write+0xbd/0x1e0
>>> [ 819.774841] [<ffffffff811861d9>] SyS_write+0x49/0xa0
>>> [ 819.774939] [<ffffffff816d1052>] system_call_fastpath+0x16/0x1b
>>> [ 819.775055] Code: 89 f8 48 89 e5 f6 82 c0 a6 84 81 20 74 15 0f 1f 44 00 00 48 83 c0 01 0f b6 10 f6 82 c0 a6 84 81 20 75 f0 5d c3 66 0f 1f 44 00 00 <80> 3f 00 55 48 89 e5 74 15 48 89 f8 0f 1f 40 00 48 83 c0 01 80
>>> [ 819.775760] RIP [<ffffffff813381c0>] skip_spaces+0x30/0x30
>>> [ 819.775881] RSP <ffff8804015cbc70>
>>> [ 819.775949] CR2: 0000000000000000
>>> [ 819.794175] ---[ end trace c4ef25127039952e ]---
>>>
>>> Signed-off-by: Shuah Khan <shuah.kh@...sung.com>
>>> ---
>>> drivers/base/power/wakeup.c | 3 +++
>>> 1 file changed, 3 insertions(+)
>>>
>>> diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
>>> index 2d56f41..a605f0d 100644
>>> --- a/drivers/base/power/wakeup.c
>>> +++ b/drivers/base/power/wakeup.c
>>> @@ -223,6 +223,9 @@ int device_wakeup_enable(struct device *dev)
>>> if (!dev || !dev->power.can_wakeup)
>>> return -EINVAL;
>>>
>>> + if (WARN_ON(!dev_name(dev)))
>>> + return -EINVAL;
>>> +
>>> ws = wakeup_source_register(dev_name(dev));
>>
>> Shouldn't wakeup_source_register() just handle a NULL for a name better?
>
> In fact, it does.
>
> The bug is in wakeup_source_activate() and that's because it passes ws->name
> to trace_wakeup_source_activate() which then doesn't bother to check it against
> NULL.
>
> So the solution here is to check ws->name before attempting to pass
> it to trace_wakeup_source_activate() in wakeup_source_activate(). It is
> actually valid to have a wakeup source with a NULL name and it shouldn't
> blow up like this.
>
> Thanks,
> Rafael
>
Rafael beat me to it. Yes adding the following to
DECLARE_EVENT_CLASS(wakeup_source, should take care of the problem:
const char *tmp_i = name ? name : "ws no name";
__assign_str(name, tmp_i);
should make trace_wakeup_source_activate() not blow up. I did consider
this as one of the fixes to the oops. Would you rather see this fix
instead of this change to device_wakeup_enable()?
-- Shuah
--
Shuah Khan
Senior Linux Kernel Developer - Open Source Group
Samsung Research America(Silicon Valley)
shuah.kh@...sung.com | (970) 672-0658
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