linux-hardening - Re: [PATCH][next] xfs: Use kvcalloc() instead of kvzalloc()

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Date:   Mon, 11 Oct 2021 15:58:38 -0700
From:   "Darrick J. Wong" <djwong@...nel.org>
To:     "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc:     linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org
Subject: Re: [PATCH][next] xfs: Use kvcalloc() instead of kvzalloc()

On Tue, Sep 28, 2021 at 05:33:07PM -0500, Gustavo A. R. Silva wrote:
> Use 2-factor argument multiplication form kvcalloc() instead of
> kvzalloc().
> 
> Link: https://github.com/KSPP/linux/issues/162
> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>

Oooh, fun, checks for multiplication overflows.

Reviewed-by: Darrick J. Wong <djwong@...nel.org>

--D

> ---
>  fs/xfs/xfs_ioctl.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index 0c795dc093ef..174cd8950cb6 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -1547,7 +1547,7 @@ xfs_ioc_getbmap(
>  	if (bmx.bmv_count > ULONG_MAX / recsize)
>  		return -ENOMEM;
>  
> -	buf = kvzalloc(bmx.bmv_count * sizeof(*buf), GFP_KERNEL);
> +	buf = kvcalloc(bmx.bmv_count, sizeof(*buf), GFP_KERNEL);
>  	if (!buf)
>  		return -ENOMEM;
>  
> @@ -1601,11 +1601,11 @@ xfs_ioc_getfsmap(
>  	 */
>  	count = min_t(unsigned int, head.fmh_count,
>  			131072 / sizeof(struct fsmap));
> -	recs = kvzalloc(count * sizeof(struct fsmap), GFP_KERNEL);
> +	recs = kvcalloc(count, sizeof(struct fsmap), GFP_KERNEL);
>  	if (!recs) {
>  		count = min_t(unsigned int, head.fmh_count,
>  				PAGE_SIZE / sizeof(struct fsmap));
> -		recs = kvzalloc(count * sizeof(struct fsmap), GFP_KERNEL);
> +		recs = kvcalloc(count, sizeof(struct fsmap), GFP_KERNEL);
>  		if (!recs)
>  			return -ENOMEM;
>  	}
> -- 
> 2.27.0
>