Re: [PATCH] dax/fsdev: fix uninitialized kaddr in fsdev_dax_zero_page_range()

[Dave Jiang]

On 4/12/26 8:50 AM, John Groves wrote:
> From: John Groves <John@xxxxxxxxxx>
> 
> __fsdev_dax_direct_access() returns -EFAULT without setting *kaddr when
> dax_pgoff_to_phys() returns -1 (pgoff out of range). The return value
> was ignored, leaving kaddr uninitialized before being passed to
> fsdev_write_dax().
> 
> Check the return value and propagate the error.
> 
> Thanks to Dan Carpenter and the smatch project for reporting this.
> 
> Signed-off-by: John Groves <john@xxxxxxxxxx>

Reviewed-by: Dave Jiang <dave.jiang@xxxxxxxxx>


> ---
>  drivers/dax/fsdev.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/dax/fsdev.c b/drivers/dax/fsdev.c
> index 4499d9621f33..188b2526bee4 100644
> --- a/drivers/dax/fsdev.c
> +++ b/drivers/dax/fsdev.c
> @@ -80,9 +80,12 @@ static int fsdev_dax_zero_page_range(struct dax_device *dax_dev,
>  			pgoff_t pgoff, size_t nr_pages)
>  {
>  	void *kaddr;
> +	long rc;
>  
>  	WARN_ONCE(nr_pages > 1, "%s: nr_pages > 1\n", __func__);
> -	__fsdev_dax_direct_access(dax_dev, pgoff, 1, DAX_ACCESS, &kaddr, NULL);
> +	rc = __fsdev_dax_direct_access(dax_dev, pgoff, 1, DAX_ACCESS, &kaddr, NULL);
> +	if (rc < 0)
> +		return rc;
>  	fsdev_write_dax(kaddr, ZERO_PAGE(0), 0, PAGE_SIZE);
>  	return 0;
>  }
> 
> base-commit: 2ae624d5a555d47a735fb3f4d850402859a4db77