linux-kernel - [08/34] mmc: atmel-mci: prevent kernel oops while removing card

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Message-Id: <20100524230350.055339389@clark.site>
Date:	Mon, 24 May 2010 15:59:40 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	Haavard Skinnemoen <hskinnemoen@...el.com>,
	<linux-mmc@...r.kernel.org>
Subject: [08/34] mmc: atmel-mci: prevent kernel oops while removing card

2.6.34-stable review patch.  If anyone has any objections, please let us know.

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

From: Nicolas Ferre <nicolas.ferre@...el.com>

commit 009a891b22395fc86e5f34057d79fffee4509ab5 upstream.

The removing of an SD card in certain circumstances can lead to a kernel
oops if we do not make sure that the "data" field of the host structure is
valid.  This patch adds a test in atmci_dma_cleanup() function and also
calls atmci_stop_dma() before throwing away the reference to data.

Signed-off-by: Nicolas Ferre <nicolas.ferre@...el.com>
Cc: Haavard Skinnemoen <hskinnemoen@...el.com>
Cc: <linux-mmc@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/mmc/host/atmel-mci.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/drivers/mmc/host/atmel-mci.c
+++ b/drivers/mmc/host/atmel-mci.c
@@ -530,9 +530,10 @@ static void atmci_dma_cleanup(struct atm
 {
 	struct mmc_data			*data = host->data;
 
-	dma_unmap_sg(&host->pdev->dev, data->sg, data->sg_len,
-		     ((data->flags & MMC_DATA_WRITE)
-		      ? DMA_TO_DEVICE : DMA_FROM_DEVICE));
+	if (data)
+		dma_unmap_sg(&host->pdev->dev, data->sg, data->sg_len,
+			     ((data->flags & MMC_DATA_WRITE)
+			      ? DMA_TO_DEVICE : DMA_FROM_DEVICE));
 }
 
 static void atmci_stop_dma(struct atmel_mci *host)
@@ -1037,8 +1038,8 @@ static void atmci_command_complete(struc
 			"command error: status=0x%08x\n", status);
 
 		if (cmd->data) {
-			host->data = NULL;
 			atmci_stop_dma(host);
+			host->data = NULL;
 			mci_writel(host, IDR, MCI_NOTBUSY
 					| MCI_TXRDY | MCI_RXRDY
 					| ATMCI_DATA_ERROR_FLAGS);


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