linux-kernel - Re: [dm-devel] [PATCH] dm integrity: Use struct_group() to zero struct journal_sector

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Message-ID: <20211213232538.GB60133@embeddedor>
Date:   Mon, 13 Dec 2021 17:25:38 -0600
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     Alasdair Kergon <agk@...hat.com>, dm-devel@...hat.com,
        linux-hardening@...r.kernel.org, Mike Snitzer <snitzer@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [dm-devel] [PATCH] dm integrity: Use struct_group() to zero
 struct journal_sector

On Thu, Nov 18, 2021 at 12:36:40PM -0800, Kees Cook wrote:
> In preparation for FORTIFY_SOURCE performing compile-time and run-time
> field bounds checking for memset(), avoid intentionally writing across
> neighboring fields.
> 
> Add struct_group() to mark region of struct journal_sector that should be
> initialized to zero.
> 
> Signed-off-by: Kees Cook <keescook@...omium.org>

Reviewed-by: Gustavo A. R. Silva <gustavoars@...nel.org>

Thanks
--
Gustavo

> ---
>  drivers/md/dm-integrity.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
> index 6319deccbe09..163c94ca4e5c 100644
> --- a/drivers/md/dm-integrity.c
> +++ b/drivers/md/dm-integrity.c
> @@ -121,8 +121,10 @@ struct journal_entry {
>  #define JOURNAL_MAC_SIZE		(JOURNAL_MAC_PER_SECTOR * JOURNAL_BLOCK_SECTORS)
>  
>  struct journal_sector {
> -	__u8 entries[JOURNAL_SECTOR_DATA - JOURNAL_MAC_PER_SECTOR];
> -	__u8 mac[JOURNAL_MAC_PER_SECTOR];
> +	struct_group(sectors,
> +		__u8 entries[JOURNAL_SECTOR_DATA - JOURNAL_MAC_PER_SECTOR];
> +		__u8 mac[JOURNAL_MAC_PER_SECTOR];
> +	);
>  	commit_id_t commit_id;
>  };
>  
> @@ -2870,7 +2872,8 @@ static void init_journal(struct dm_integrity_c *ic, unsigned start_section,
>  		wraparound_section(ic, &i);
>  		for (j = 0; j < ic->journal_section_sectors; j++) {
>  			struct journal_sector *js = access_journal(ic, i, j);
> -			memset(&js->entries, 0, JOURNAL_SECTOR_DATA);
> +			BUILD_BUG_ON(sizeof(js->sectors) != JOURNAL_SECTOR_DATA);
> +			memset(&js->sectors, 0, sizeof(js->sectors));
>  			js->commit_id = dm_integrity_commit_id(ic, i, j, commit_seq);
>  		}
>  		for (j = 0; j < ic->journal_section_entries; j++) {
> -- 
> 2.30.2
> 
> --
> dm-devel mailing list
> dm-devel@...hat.com
> https://listman.redhat.com/mailman/listinfo/dm-devel
> 
> 
> 
>

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