[3.5.y.z extended stable] Patch "mtd: m25p80: fix allocation size" has been added to staging queue

Luis Henriques luis.henriques at canonical.com
Fri Nov 29 14:02:26 UTC 2013

This is a note to let you know that I have just added a patch titled

    mtd: m25p80: fix allocation size

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:


If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



>From 51e2746bcdeafc63ae7e26ef0c75cf769faa18f7 Mon Sep 17 00:00:00 2001
From: Brian Norris <computersforpeace at gmail.com>
Date: Wed, 24 Jul 2013 18:32:07 -0700
Subject: mtd: m25p80: fix allocation size

commit 778d226a1462572b51d6777cdb1d611543410cb4 upstream.

This patch fixes two memory errors:

1. During a probe failure (in mtd_device_parse_register?) the command
   buffer would not be freed.

2. The command buffer's size is determined based on the 'fast_read'
   boolean, but the assignment of fast_read is made after this
   allocation. Thus, the buffer may be allocated "too small".

To fix the first, just switch to the devres version of kzalloc.

To fix the second, increase MAX_CMD_SIZE unconditionally. It's not worth
saving a byte to fiddle around with the conditions here.

This problem was reported by Yuhang Wang a while back.

Signed-off-by: Brian Norris <computersforpeace at gmail.com>
Reported-by: Yuhang Wang <wangyuhang2014 at gmail.com>
Reviewed-by: Sourav Poddar <sourav.poddar at ti.com>
[ luis: backported to 3.5: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 drivers/mtd/devices/m25p80.c | 19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index 5d0d68c..e857734 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -71,7 +71,7 @@

 /* Define max times to check status register before we give up. */
 #define	MAX_READY_WAIT_JIFFIES	(40 * HZ)	/* M25P16 specs 40s max chip erase */
-#define	MAX_CMD_SIZE		5
+#define	MAX_CMD_SIZE		6

@@ -848,14 +848,13 @@ static int __devinit m25p_probe(struct spi_device *spi)

-	flash = kzalloc(sizeof *flash, GFP_KERNEL);
+	flash = devm_kzalloc(&spi->dev, sizeof(*flash), GFP_KERNEL);
 	if (!flash)
 		return -ENOMEM;
-	flash->command = kmalloc(MAX_CMD_SIZE + FAST_READ_DUMMY_BYTE, GFP_KERNEL);
-	if (!flash->command) {
-		kfree(flash);
+	flash->command = devm_kzalloc(&spi->dev, MAX_CMD_SIZE, GFP_KERNEL);
+	if (!flash->command)
 		return -ENOMEM;
-	}

 	flash->spi = spi;
@@ -952,14 +951,10 @@ static int __devinit m25p_probe(struct spi_device *spi)
 static int __devexit m25p_remove(struct spi_device *spi)
 	struct m25p	*flash = dev_get_drvdata(&spi->dev);
-	int		status;

 	/* Clean up MTD stuff. */
-	status = mtd_device_unregister(&flash->mtd);
-	if (status == 0) {
-		kfree(flash->command);
-		kfree(flash);
-	}
+	mtd_device_unregister(&flash->mtd);
 	return 0;


More information about the kernel-team mailing list