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From: Vince Weaver <vincent.weaver@maine.edu>
To: Vince Weaver <vincent.weaver@maine.edu>
Cc: Huang Rui <ray.huang@amd.com>,
	Peter Zijlstra <peterz@infradead.org>,
	linux-kernel@vger.kernel.org, Borislav Petkov <bp@suse.de>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>
Subject: Re: perf: fuzzer crashes immediately on AMD system
Date: Mon, 22 Aug 2016 22:54:32 -0400 (EDT)	[thread overview]
Message-ID: <alpine.DEB.2.20.1608222250120.29115@macbook-air> (raw)
In-Reply-To: <alpine.DEB.2.20.1608222057360.29115@macbook-air>

> > > > 
> > > > 	perf stat -a -e amd_nb/config=0x37,config1=0x20/ /bin/ls
> 	amd_uncore_find_online_sibling()
> function is broken. 

and that's the problem.  uncore_find_online_sibling() does all kinds of 
wrong things including sticking active uncore structures in 
uncore->free_when_cpu_online

Then uncore_online() comes along and frees those structures.

Then some other part of the kernel comes and re-uses the free'd data.

Then when we try to start an event, all of the fields are invalid because 
the uncore pointer is pointing to re-used data.

I don't have a patch because I am not 100% clear on what 
uncore_find_online_sibling() is doing in the first place.

Vince

  reply	other threads:[~2016-08-23  2:54 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-18 14:32 Vince Weaver
2016-08-18 14:46 ` Vince Weaver
2016-08-19 10:01   ` Peter Zijlstra
2016-08-19 10:56     ` Peter Zijlstra
2016-08-19 15:03     ` Vince Weaver
2016-08-19 16:38       ` Vince Weaver
2016-08-20  4:44     ` Vince Weaver
2016-08-22 11:16     ` Huang Rui
2016-08-23  1:02       ` Vince Weaver
2016-08-23  2:54         ` Vince Weaver [this message]
2016-08-23  8:45           ` Peter Zijlstra
2016-08-23 11:53             ` Vince Weaver
2016-08-24  9:19               ` Ingo Molnar
2016-08-24 13:20                 ` Vince Weaver

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