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Date:   Tue, 12 Nov 2019 00:37:41 +0100 (CET)
From:   Thomas Gleixner <tglx@linutronix.de>
To:     Bartosz Golaszewski <bgolaszewski@baylibre.com>
cc:     Daniel Lezcano <daniel.lezcano@linaro.org>,
        Colin King <colin.king@canonical.com>,
        LKML <linux-kernel@vger.kernel.org>,
        kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] clocksource/drivers/davinci: fix memory leak on clockevent
 on error return
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Message-ID: <alpine.DEB.2.21.1911120033220.1833@nanos.tec.linutronix.de>
References: <20191109155836.223635-1-colin.king@canonical.com> <CAMpxmJVC5GGhR0z_4CkF7Opfw-5HpEKD8fUrKsgBZTbz0wDd-Q@mail.gmail.com>
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Bartosz,

On Sun, 10 Nov 2019, Bartosz Golaszewski wrote:
> sob., 9 lis 2019 o 16:58 Colin King <colin.king@canonical.com> napisał(a):
> >
> > From: Colin Ian King <colin.king@canonical.com>
> >
> > In the case where request_irq fails, the return path does not kfree
> > clockevent and hence we have a memory leak.  Fix this by kfree'ing

s/we have/creates/  or whatever verb you prefer.

> > clockevent before returning.
> >
> > Addresses-Coverity: ("Resource leak")
> > Fixes: 721154f972aa ("clocksource/drivers/davinci: Add support for clockevents")
> > Signed-off-by: Colin Ian King <colin.king@canonical.com>
> > ---
> >  drivers/clocksource/timer-davinci.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/clocksource/timer-davinci.c b/drivers/clocksource/timer-davinci.c
> > index 62745c962049..910d4d2f0d64 100644
> > --- a/drivers/clocksource/timer-davinci.c
> > +++ b/drivers/clocksource/timer-davinci.c
> > @@ -299,6 +299,7 @@ int __init davinci_timer_register(struct clk *clk,
> >                          "clockevent/tim12", clockevent);
> >         if (rv) {
> >                 pr_err("Unable to request the clockevent interrupt");
> > +               kfree(clockevent);
> >                 return rv;
> >         }
> >
> > --
> > 2.20.1
> >
> 
> Hi Daniel,
> 
> this is what I think the third time someone tries to "fix" this
> driver's "memory leaks". I'm not sure what the general approach in
> clocksource is but it doesn't make sense to free resources on
> non-recoverable errors, does it? Should I add a comment about it or
> you'll just take those "fixes" to stop further such submissions?

There are two ways to deal with that:

  1) If the error is really unrecoverable, panic right there. No point
     to continue.

  2) If there is even a minimal chance to survive, free the memory and
     return.

Adding a comment is just a useless non-option.

Thanks,

	tglx
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