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

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Message-Id: <1424277299-24964-1-git-send-email-geert+renesas@glider.be>
Date:	Wed, 18 Feb 2015 17:34:59 +0100
From:	Geert Uytterhoeven <geert+renesas@...der.be>
To:	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>
Cc:	linux-mmc@...r.kernel.org, linux-sh@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Geert Uytterhoeven <geert+renesas@...der.be>
Subject: [PATCH] mmc: tmio: Remove bogus un-initialization in tmio_mmc_host_free()

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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