2014-01-22 16:27:38

by Fabian Frédérick

Subject: [PATCH 1/1 RESEND] mtd: block2mtd: char mtd major and erasesize parameter check + mutex_destroy

-Deny use of a char mtd device to map as block device.
-mutex_init when mtd structure is available.
-fixme applied : check device size is a multiple of erasesize.
-mutex_destroy on each device in block2mtd_exit and add_device failure.

Signed-off-by: Fabian Frederick <[email protected]>
---
drivers/mtd/devices/block2mtd.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/mtd/devices/block2mtd.c b/drivers/mtd/devices/block2mtd.c
index d9fd87a..be67731 100644
--- a/drivers/mtd/devices/block2mtd.c
+++ b/drivers/mtd/devices/block2mtd.c
@@ -209,7 +209,6 @@ static void block2mtd_free_device(struct block2mtd_dev *dev)
}


-/* FIXME: ensure that mtd->size % erase_size == 0 */
static struct block2mtd_dev *add_device(char *devname, int erase_size)
{
const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
@@ -244,21 +243,27 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size)
}
dev->blkdev = bdev;

- if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
+ if ((MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) ||
+ (MAJOR(bdev->bd_dev) == MTD_CHAR_MAJOR)) {
pr_err("attempting to use an MTD device as a block device\n");
goto devinit_err;
}

- mutex_init(&dev->write_mutex);

/* Setup the MTD structure */
/* make the name contain the block device in */
name = kasprintf(GFP_KERNEL, "block2mtd: %s", devname);
+
if (!name)
goto devinit_err;
+
+ if ((long)dev->blkdev->bd_inode->i_size % erase_size) {
+ pr_err("erasesize must be a divisor of device size\n");
+ goto devinit_err;
+ }

+ mutex_init(&dev->write_mutex);
dev->mtd.name = name;
-
dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
dev->mtd.erasesize = erase_size;
dev->mtd.writesize = 1;
@@ -274,7 +279,7 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size)

if (mtd_device_register(&dev->mtd, NULL, 0)) {
/* Device didn't get added, so free the entry */
- goto devinit_err;
+ goto register_err;
}
list_add(&dev->list, &blkmtd_device_list);
pr_info("mtd%d: [%s] erase_size = %dKiB [%d]\n",
@@ -283,6 +288,8 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size)
dev->mtd.erasesize >> 10, dev->mtd.erasesize);
return dev;

+register_err:
+ mutex_destroy(&dev->write_mutex);
devinit_err:
block2mtd_free_device(dev);
return NULL;
@@ -448,6 +455,7 @@ static void block2mtd_exit(void)
struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
block2mtd_sync(&dev->mtd);
mtd_device_unregister(&dev->mtd);
+ mutex_destroy(&dev->write_mutex);
pr_info("mtd%d: [%s] removed\n",
dev->mtd.index,
dev->mtd.name + strlen("block2mtd: "));
--
1.8.1.4

2014-01-23 12:43:11

by Ezequiel Garcia

Subject: Re: [PATCH 1/1 RESEND] mtd: block2mtd: char mtd major and erasesize parameter check + mutex_destroy

Hi Fabian,

On Wed, Jan 22, 2014 at 04:28:43PM +0800, Fabian Frederick wrote:
> -Deny use of a char mtd device to map as block device.
> -mutex_init when mtd structure is available.
> -fixme applied : check device size is a multiple of erasesize.
> -mutex_destroy on each device in block2mtd_exit and add_device failure.
>

Hm... that sound like a lot of work for a single patch :-)

Care to chop it and submit a one-thing-per-patch series?

Thanks!
--
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com