linux-kernel - Re: [PATCH 1/4] ftrace: Fix MATCH_END

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Message-ID: <20091211174632.GC5094@nowhere>
Date:	Fri, 11 Dec 2009 18:46:36 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Frederic Riss <frederic.riss@...il.com>,
	Li Zefan <lizf@...fujitsu.com>, Ingo Molnar <mingo@...e.hu>,
	Wenji Huang <wenji.huang@...cle.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/4] ftrace: Fix MATCH_END_ONLY filter matching

On Fri, Dec 11, 2009 at 10:10:31AM -0500, Steven Rostedt wrote:
> On Fri, 2009-12-11 at 13:27 +0100, Frederic Weisbecker wrote:
> > On Fri, Dec 11, 2009 at 01:20:04PM +0100, Frederic Riss wrote:
> > > 2009/12/11 Li Zefan <lizf@...fujitsu.com>:
> > > > For '*foo' pattern, we should allow any string ending with
> > > > 'foo', but ftrace filter incorrectly disallows strings
> > > > like bar_foo_foo:
> > > [...]
> > > >        case MATCH_END_ONLY:
> > > > -               ptr = strstr(str, regex);
> > > > -               if (ptr && (ptr[len] == 0))
> > > > +               slen = strlen(str);
> > > > +               if (slen >= len && memcpy(str + slen - len, regex, len))
> > > >                        matched = 1;
> > > 
> > > Shouldn't that be memcmp() == 0? I don't see how memcpy might serve as
> > > a compare operator.
> > > 
> > > Fred.
> > 
> > 
> > Oh you're right, I reviewed it too quickly. Perhaps the star's
> > alignment made it possible for only one Frederic to review it
> > the right way...
> > 
> 
> The stars are still fuzzy to me. How does memcpy work here?


It doesn't, I guess Li intended to use memcmp.

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