linux-kernel - Re: perf/ftrace: fuzzer triggers another warning with PERF_EVENT_IOC_SET

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Message-ID: <20150618132533.47ddf3eb@gandalf.local.home>
Date:	Thu, 18 Jun 2015 13:25:33 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Vince Weaver <vincent.weaver@...ne.edu>
Cc:	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>
Subject: Re: perf/ftrace: fuzzer triggers another warning with
 PERF_EVENT_IOC_SET_FILTER

On Wed, 17 Jun 2015 19:32:26 -0400 (EDT)
Vince Weaver <vincent.weaver@...ne.edu> wrote:

> 
> The fuzzer triggered another warning in the PERF_EVENT_IOC_SET_FILTER 
> code.  This is with the previous filter patch applied.
> 
> >From what I can tell the filter was:
> nfs4:nfs4_fsinfo 
> (((fhandle~601)&&valid&809)&&common_type>=860) 

Hmm, I can't trigger this with the filter file, can you?

 echo '(((fhandle~601)&&valid&809)&&common_type>=860)' > \
  /sys/kernel/debug/tracing/events/nfs4/nfs4_fsinfo/filter

I'll write a user app to use the perf syscall and see if that is
different, but in the mean time, can you try the above.

Thanks!

-- Steve

> 
> The warning in question:
> 	WARN_ON_ONCE(cnt < 0);
> in check_preds().
> 
> [65903.660154] WARNING: CPU: 1 PID: 731 at kernel/trace/trace_events_filter.c:1388 replace_preds+0x2e4/0xa50()
> [65903.748080] CPU: 1 PID: 731 Comm: perf_fuzzer Tainted: G        W       4.1.0-rc8+ #157
> [65903.757203] Hardware name: LENOVO 10AM000AUS/SHARKBAY, BIOS FBKT72AUS 01/26/2014
> [65903.765711]  ffffffff81a1ac00 ffff880117117cb8 ffffffff816d7419 0000000000000000
> [65903.774323]  0000000000000000 ffff880117117cf8 ffffffff81072eba 0000000000000005
> [65903.782924]  0000000000000003 ffff8800366bd018 ffff8800366bd000 ffff8800cf3e9220
> [65903.791516] Call Trace:
> [65903.794688]  [<ffffffff816d7419>] dump_stack+0x45/0x57
> [65903.800732]  [<ffffffff81072eba>] warn_slowpath_common+0x8a/0xc0
> [65903.807712]  [<ffffffff81072faa>] warn_slowpath_null+0x1a/0x20
> [65903.814477]  [<ffffffff8114b1c4>] replace_preds+0x2e4/0xa50
> [65903.820974]  [<ffffffff8114c2c3>] ? ftrace_profile_set_filter+0x23/0x100
> [65903.828640]  [<ffffffff8114b9b2>] create_filter+0x82/0xb0
> [65903.834917]  [<ffffffff8114c2f4>] ftrace_profile_set_filter+0x54/0x100
> [65903.842436]  [<ffffffff811909eb>] ? strndup_user+0x4b/0xc0
> [65903.848794]  [<ffffffff81166290>] perf_ioctl+0x170/0x4d0
> [65903.854959]  [<ffffffff812023d0>] do_vfs_ioctl+0x2e0/0x4e0
> [65903.861286]  [<ffffffff816dcdfe>] ? mutex_unlock+0xe/0x10
> [65903.867492]  [<ffffffff81164756>] ? perf_event_task_enable+0xb6/0xd0
> [65903.874754]  [<ffffffff81202651>] SyS_ioctl+0x81/0xa0
> [65903.880655]  [<ffffffff816df372>] system_call_fastpath+0x16/0x7a
> [65903.887534] ---[ end trace 48137d0593a025d9 ]---

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