Re: [PATCH] xfs: sanitize da node pad field on write

["Darrick J. Wong" <djwong@kernel.org>]

On Tue, Apr 21, 2026 at 06:43:12AM +0100, Yuto Ohnuki wrote:
> The DA node block header (xfs_da3_node_hdr) contains a __pad32 field
> that should always be zero. Prior to commit a45086e27dfa21 ("xfs:
> validate metadata LSNs against log on v5 superblocks"),
> xfs_da3_node_create() did not zero the full header, so __pad32 could
> contain stale data on older filesystems.
> 
> Clear this field in the write verifier to ensure it is corrected
> whenever the block is next written to disk.
> 
> Suggested-by: "Darrick J. Wong" <djwong@kernel.org>
> Signed-off-by: Yuto Ohnuki <ytohnuki@amazon.com>
> ---
>  fs/xfs/libxfs/xfs_da_btree.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c
> index ad801b7bd2dd..f6054a47d24c 100644
> --- a/fs/xfs/libxfs/xfs_da_btree.c
> +++ b/fs/xfs/libxfs/xfs_da_btree.c
> @@ -318,6 +318,8 @@ xfs_da3_node_write_verify(
>  	if (bip)
>  		hdr3->info.lsn = cpu_to_be64(bip->bli_item.li_lsn);
>  
> +	hdr3->__pad32 = 0;

Looks good to me, thanks for clearing this todo :)

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

--D

> +
>  	xfs_buf_update_cksum(bp, XFS_DA3_NODE_CRC_OFF);
>  }
>  
> -- 
> 2.50.1
> 
> 
> 
> 
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