linux-kernel - Re: [PATCH] mmc: tmio: Remove bogus un-initialization in tmio_mmc_host

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Date:	Thu, 5 Mar 2015 11:08:58 +0100
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Geert Uytterhoeven <geert+renesas@...der.be>
Cc:	Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
	Ian Molton <ian.molton@...ethink.co.uk>,
	Chris Ball <chris@...ntf.net>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Linux MMC List <linux-mmc@...r.kernel.org>,
	Linux-sh list <linux-sh@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mmc: tmio: Remove bogus un-initialization in tmio_mmc_host_free()

Ping?

On Wed, Feb 18, 2015 at 5:34 PM, Geert Uytterhoeven
<geert+renesas@...der.be> wrote:
> If CONFIG_DEBUG_SLAB=y:
>
>     sh_mobile_sdhi ee100000.sd: Got CD GPIO
>     sh_mobile_sdhi ee100000.sd: Got WP GPIO
>     platform ee100000.sd: Driver sh_mobile_sdhi requests probe deferral
>     ...
>     Slab corruption (Not tainted): kmalloc-1024 start=ed8b3c00, len=1024
>     2d0: 00 00 00 00 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  ....kkkkkkkkkkkk
>     Prev obj: start=ed8b3800, len=1024
>     000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  kkkkkkkkkkkkkkkk
>     010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  kkkkkkkkkkkkkkkk
>
> Struct tmio_mmc_host is embedded inside struct mmc_host, and thus is
> freed by the call to mmc_free_host(). Hence it must not be written to
> afterwards, as that will corrupt freed (and perhaps already reused)
> memory.
>
> Fixes: 94b110aff8679b14 ("mmc: tmio: add tmio_mmc_host_alloc/free()")
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> ---
>  drivers/mmc/host/tmio_mmc_pio.c | 2 --
>  1 file changed, 2 deletions(-)
>
> diff --git a/drivers/mmc/host/tmio_mmc_pio.c b/drivers/mmc/host/tmio_mmc_pio.c
> index a31c3573d386f8c6..dba7e1c19dd758e7 100644
> --- a/drivers/mmc/host/tmio_mmc_pio.c
> +++ b/drivers/mmc/host/tmio_mmc_pio.c
> @@ -1073,8 +1073,6 @@ EXPORT_SYMBOL(tmio_mmc_host_alloc);
>  void tmio_mmc_host_free(struct tmio_mmc_host *host)
>  {
>         mmc_free_host(host->mmc);
> -
> -       host->mmc = NULL;
>  }
>  EXPORT_SYMBOL(tmio_mmc_host_free);
>
> --
> 1.9.1
--
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