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

[Kamal Mostafa]

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

    mtd: m25p80: fix allocation size

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.14.

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

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 7ca32f44e8705aca1538ea00e43a45a581703fe4 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>
[ kamal: backport to 3.8 (context) ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/mtd/devices/m25p80.c | 20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index 4eeeb2d..ae5ccf5 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

 #define JEDEC_MFR(_jedec_id)	((_jedec_id) >> 16)

@@ -861,15 +861,13 @@ static int 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 + (flash->fast_read ? 1 : 0),
-					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;
 	mutex_init(&flash->lock);
@@ -976,14 +974,10 @@ static int m25p_probe(struct spi_device *spi)
 static int 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;
 }

--
1.8.3.2