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Message-ID: <4392832.qmtCDxa3F5@vostro.rjw.lan> Date: Fri, 22 Nov 2013 23:18:09 +0100 From: "Rafael J. Wysocki" <rjw@...ysocki.net> To: Shuah Khan <shuah.kh@...sung.com> Cc: anton@...msg.org, dwmw2@...radead.org, rostedt@...dmis.org, fweisbec@...il.com, mingo@...hat.com, gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org, shuahkhan@...il.com, stable@...r.kernel.org Subject: Re: [PATCH v3 2/2] tracing: Fix Oops from NULL pointer dereference from __assign_str On Friday, November 22, 2013 10:54:29 AM Shuah Khan wrote: > Tracing infrastructure routine __assign_str doesn't handle null strings. > As a result when an trace event passes in a null string, kernel panics > when skip_spaces() is invoked on the string. The following oops occurred > when a null wakeup source name is specified. > > 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 tracing infrastructure to be more robust in handling null strings in > __assign_string() and __string(). With this change null string is handled > gracefully and replacing it with "(null)" when trace is generated. This will > address the problem at the tracing infrastructure level which is better than > fixing individual tracepoint code. > > Trace after the fix: > bash-2177 [000] d... 583.560106: wakeup_source_activate: (null) state=0x20001 > kworker/0:2-378 [000] d... 583.560714: wakeup_source_deactivate: (null) 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@...sung.com> > Cc: stable@...r.kernel.org Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com> > --- > include/trace/ftrace.h | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h > index 52594b2..79f4639 100644 > --- a/include/trace/ftrace.h > +++ b/include/trace/ftrace.h > @@ -372,7 +372,9 @@ ftrace_define_fields_##call(struct ftrace_event_call *event_call) \ > __data_size += (len) * sizeof(type); > > #undef __string > -#define __string(item, src) __dynamic_array(char, item, strlen(src) + 1) > +#define __string(item, src) \ > + __dynamic_array(char, item, \ > + strlen((const char *)src ? (const char *)src : "(null)") + 1) > > #undef DECLARE_EVENT_CLASS > #define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \ > @@ -501,7 +503,8 @@ static inline notrace int ftrace_get_offsets_##call( \ > > #undef __assign_str > #define __assign_str(dst, src) \ > - strcpy(__get_str(dst), src); > + strcpy(__get_str(dst), \ > + ((const char *)src ? (const char *)src : "(null)")) > > #undef TP_fast_assign > #define TP_fast_assign(args...) args > -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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