linux-kernel - [ 49/57] mmc: sdhci: fix NULL dereference in sdhci

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Message-Id: <20121115040936.151320638@linuxfoundation.org>
Date:	Wed, 14 Nov 2012 20:11:57 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	alan@...rguk.ukuu.org.uk, Chris Ball <cjb@...top.org>
Subject: [ 49/57] mmc: sdhci: fix NULL dereference in sdhci_request() tuning

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chris Ball <cjb@...top.org>

commit 14efd957209461bbdf285bf0d67e931955d04a4c upstream.

Commit 473b095a72a9 ("mmc: sdhci: fix incorrect command used in tuning")
introduced a NULL dereference at resume-time if an SD 3.0 host controller
raises the SDHCI_NEEDS_TUNING flag while no card is inserted.  Seen on an
OLPC XO-4 with sdhci-pxav3, but presumably affects other controllers too.

Signed-off-by: Chris Ball <cjb@...top.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/mmc/host/sdhci.c |   21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1294,16 +1294,19 @@ static void sdhci_request(struct mmc_hos
 		 */
 		if ((host->flags & SDHCI_NEEDS_RETUNING) &&
 		    !(present_state & (SDHCI_DOING_WRITE | SDHCI_DOING_READ))) {
-			/* eMMC uses cmd21 while sd and sdio use cmd19 */
-			tuning_opcode = mmc->card->type == MMC_TYPE_MMC ?
-				MMC_SEND_TUNING_BLOCK_HS200 :
-				MMC_SEND_TUNING_BLOCK;
-			spin_unlock_irqrestore(&host->lock, flags);
-			sdhci_execute_tuning(mmc, tuning_opcode);
-			spin_lock_irqsave(&host->lock, flags);
+			if (mmc->card) {
+				/* eMMC uses cmd21 but sd and sdio use cmd19 */
+				tuning_opcode =
+					mmc->card->type == MMC_TYPE_MMC ?
+					MMC_SEND_TUNING_BLOCK_HS200 :
+					MMC_SEND_TUNING_BLOCK;
+				spin_unlock_irqrestore(&host->lock, flags);
+				sdhci_execute_tuning(mmc, tuning_opcode);
+				spin_lock_irqsave(&host->lock, flags);
 
-			/* Restore original mmc_request structure */
-			host->mrq = mrq;
+				/* Restore original mmc_request structure */
+				host->mrq = mrq;
+			}
 		}
 
 		if (mrq->sbc && !(host->flags & SDHCI_AUTO_CMD23))


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