linux-kernel - Re: UBSAN: Undefined behaviour in arch/x86/events/intel/p6.c:115:29

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Date:	Thu, 19 May 2016 10:36:09 +0300 (EEST)
From:	Meelis Roos <mroos@...ux.ee>
To:	Nilay Vaish <nilayvaish@...il.com>
cc:	Linux Kernel list <linux-kernel@...r.kernel.org>, x86@...nel.org
Subject: Re: UBSAN: Undefined behaviour in
 arch/x86/events/intel/p6.c:115:29

> I think UBSAN has correctly identified a bug.  I looked at the code in
> v4.6.  In file arch/x86/events/core.c, in the function
> filter_events(), there is a loop starting at line 1554 that should go
> over 10 event counters.  But in file arch/x86/events/intel/p6.c, only
> 8 event counters have been declared at line 9.
> 
> I have a fix but do not for sure if its reasonable.  I think we should
> pass on the max_events for the pmu to filter_events() function and
> change the loop condition accordingly.  Can you apply the patch below
> and test again?  It compiles, but I have not tested it.

Seems to work - warning is gone, everythins is detected as before.

-- 
Meelis Roos (mroos@...ux.ee)