Re: [PATCH 2/2] PM: Fix Oops from NULL pointer dereference in wakeup_source_activate

[Shuah Khan <shuah.kh@samsung.com>]

On 11/20/2013 06:40 PM, Shuah Khan wrote:
> power_supply_register() calls device_init_wakeup() to register a wakeup
> source before initializing dev_name. As a result, device_wakeup_enable()
> end up registering wakeup source with a null name when wakeup_source_register()
> gets called with dev_name(dev) which is null at the time.
>
> When kernel is booted with wakeup_source_activate enabled, it will panic
> when the trace point code tries to dereference ws->name. Registering a
> a wakeup source without a name should be possible.
>
> Fix wakeup_source_activate tracepoint to check for null name and handle it
> gracefully by just using "(no name)" as the name string for the source.
>
> Fixes: commit 6791e36c4a40e8930e08669e60077eea6770c429
>
> Trace after the change:
>              bash-2008  [000] d...   610.307262: wakeup_source_activate: (no name) state=0x20001
>       kworker/0:0-2000  [000] d...   610.307287: wakeup_source_deactivate: (no name) state=0x30000
>
> Oops message:
>
> [  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@samsung.com>
> Cc: stable@vger.kernel.org
> ---
>   include/trace/events/power.h | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/include/trace/events/power.h b/include/trace/events/power.h
> index cda100d..5ba545a 100644
> --- a/include/trace/events/power.h
> +++ b/include/trace/events/power.h
> @@ -110,12 +110,14 @@ DECLARE_EVENT_CLASS(wakeup_source,
>   	TP_ARGS(name, state),
>
>   	TP_STRUCT__entry(
> -		__string(       name,           name            )
> +		__string(name,  name ? name : "(no name)")
>   		__field(        u64,            state           )
>   	),
>
>   	TP_fast_assign(
> -		__assign_str(name, name);
> +		const char *tname = name ? name : "(no name)";
> +
> +		__assign_str(name, tname);
>   		__entry->state = state;
>   	),
>
>

Adding tracing maintainers.

-- 
Shuah Khan
Senior Linux Kernel Developer - Open Source Group
Samsung Research America(Silicon Valley)
shuah.kh@samsung.com | (970) 672-0658