Re: [PATCH v2] mtd: spi-nor: fix memory leak when using debugfs_lookup()

[Michael Walle]

Am 2023-02-08 13:57, schrieb Greg Kroah-Hartman:
> When calling debugfs_lookup() the result must have dput() called on it,
> otherwise the memory will leak over time.
>
> Cc: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
> Cc: Pratyush Yadav <pratyush@xxxxxxxxxx>
> Cc: Michael Walle <michael@xxxxxxxx>
> Cc: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> Cc: Richard Weinberger <richard@xxxxxx>
> Cc: Vignesh Raghavendra <vigneshr@xxxxxx>
> Cc: linux-mtd@xxxxxxxxxxxxxxxxxxx
> Cc: stable <stable@xxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
> v2: fix up to work when module is removed and added, making the fix
>     much simpler.
>
>  drivers/mtd/spi-nor/debugfs.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/mtd/spi-nor/debugfs.c 
> b/drivers/mtd/spi-nor/debugfs.c
> index ff895f6758ea..af41fbc09a97 100644
> --- a/drivers/mtd/spi-nor/debugfs.c
> +++ b/drivers/mtd/spi-nor/debugfs.c
> @@ -242,6 +242,7 @@ void spi_nor_debugfs_register(struct spi_nor *nor)
>
>  	d = debugfs_create_dir(dev_name(nor->dev), rootdir);
>  	nor->debugfs_root = d;
> +	dput(rootdir);

rootdir might either be the return value of debugfs_lookup() or
debugfs_create_dir(). dput() is probably wrong for the latter,
right? Also there is an early return, where the dput() is missing,
too.

-michael