linux-kernel - Re: [PATCH] erofs: explicit cast blkaddr to u64 before shift operation

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Date:   Thu, 13 Apr 2023 12:27:16 +0800
From:   Jingbo Xu <jefflexu@...ux.alibaba.com>
To:     Jia Zhu <zhujia.zj@...edance.com>, linux-erofs@...ts.ozlabs.org
Cc:     linux-kernel@...r.kernel.org, yinxin.x@...edance.com,
        xiang@...nel.org
Subject: Re: [PATCH] erofs: explicit cast blkaddr to u64 before shift
 operation



On 4/13/23 11:57 AM, Jia Zhu wrote:
> We should explicitly cast @blkaddr from u32 to u64 before the shift
> operation to return the larger type.
> 
> Fixes: b1c2d99b18ff ("erofs: avoid hardcoded blocksize for subpage block support")
> Signed-off-by: Jia Zhu <zhujia.zj@...edance.com>
> ---
>  fs/erofs/data.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/erofs/data.c b/fs/erofs/data.c
> index aa7f9e4f86fb..6fe9a779fa91 100644
> --- a/fs/erofs/data.c
> +++ b/fs/erofs/data.c
> @@ -35,7 +35,7 @@ void *erofs_bread(struct erofs_buf *buf, erofs_blk_t blkaddr,
>  		  enum erofs_kmap_type type)
>  {
>  	struct inode *inode = buf->inode;
> -	erofs_off_t offset = blkaddr << inode->i_blkbits;
> +	erofs_off_t offset = (erofs_off_t)blkaddr << inode->i_blkbits;
>  	pgoff_t index = offset >> PAGE_SHIFT;
>  	struct page *page = buf->page;
>  	struct folio *folio;

LGTM. Thanks for catching this.

Reviewed-by: Jingbo Xu <jefflexu@...ux.alibaba.com>

-- 
Thanks,
Jingbo