On Tue, Dec 03, 2019 at 04:27:15PM +0800, quanyang.wang wrote:
> From: Quanyang Wang <quanyang.w...@windriver.com>
>
> When kernel booting, mount_block_root will be called to judge
> the filesystem type of root device. Then .mount function in file_system_type
> structure will do the check operation. But yaffs filesystem has a
> relaxed examination because as a filesystem for NAND Flash, it doesn't
> examinate whether the root device is the MTD NAND device. This results
> that yaffs filesystem will do mount operation even though the root device
> is a MMC card with a btrfs filesystem, and will crash kernel after
> mounting failed.
>
> Use yaffs_get_mtd_device to add strict check.
>
> Signed-off-by: Quanyang Wang <quanyang.w...@windriver.com>
> ---
> fs/yaffs2/yaffs_mtdif.c | 12 ++++++++++--
> fs/yaffs2/yaffs_vfs.c | 7 ++-----
> 2 files changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/fs/yaffs2/yaffs_mtdif.c b/fs/yaffs2/yaffs_mtdif.c
> index 4ff5741f3983..054e251a2c18 100644
> --- a/fs/yaffs2/yaffs_mtdif.c
> +++ b/fs/yaffs2/yaffs_mtdif.c
> @@ -242,17 +242,25 @@ struct mtd_info * yaffs_get_mtd_device(dev_t sdev)
> {
> struct mtd_info *mtd;
>
> - mtd = yaffs_get_mtd_device(sdev);
> -
It seems that you have fixed two issues in this patch. One issue is the
buggy yaffs_get_mtd_device(), and the other is the issue you described in
the commit log. So it would be better to separate this into two patches.
Thanks,
Kevin
> /* Check it's an mtd device..... */
> if (MAJOR(sdev) != MTD_BLOCK_MAJOR)
> return NULL; /* This isn't an mtd device */
>
> + /* Get the device */
> + mtd = get_mtd_device(NULL, MINOR(sdev));
> + if (IS_ERR_OR_NULL(mtd)) {
> + yaffs_trace(YAFFS_TRACE_ALWAYS,
> + "yaffs: MTD device %u either not valid or unavailable",
> + MINOR(sdev));
> + return NULL;
> + }
> +
> /* Check it's NAND */
> if (mtd->type != MTD_NANDFLASH) {
> yaffs_trace(YAFFS_TRACE_ALWAYS,
> "yaffs: MTD device is not NAND it's type %d",
> mtd->type);
> + put_mtd_device(mtd);
> return NULL;
> }
>
> diff --git a/fs/yaffs2/yaffs_vfs.c b/fs/yaffs2/yaffs_vfs.c
> index 61ac4e4c45d1..db77316a0f95 100644
> --- a/fs/yaffs2/yaffs_vfs.c
> +++ b/fs/yaffs2/yaffs_vfs.c
> @@ -2881,12 +2881,9 @@ static struct super_block
> *yaffs_internal_read_super(int yaffs_version,
> MAJOR(sb->s_dev), MINOR(sb->s_dev),
> yaffs_devname(sb, devname_buf));
>
> - /* Get the device */
> - mtd = get_mtd_device(NULL, MINOR(sb->s_dev));
> +
> + mtd = yaffs_get_mtd_device(sb->s_dev);
> if (!mtd) {
> - yaffs_trace(YAFFS_TRACE_ALWAYS,
> - "yaffs: MTD device %u either not valid or unavailable",
> - MINOR(sb->s_dev));
> return NULL;
> }
>
> --
> 2.17.1
>
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