Re: [PATCH 2/3] xfs: use memcpy, not strncpy, to format the attr prefix during listxattr

[Dave Chinner <david@fromorbit.com>]

On Thu, Nov 24, 2022 at 08:59:29AM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> When -Wstringop-truncation is enabled, the compiler complains about
> truncation of the null byte at the end of the xattr name prefix.  This
> is intentional, since we're concatenating the two strings together and
> do _not_ want a null byte in the middle of the name.
> 
> We've already ensured that the name buffer is long enough to handle
> prefix and name, and the prefix_len is supposed to be the length of the
> prefix string without the null byte, so use memcpy here instead.
> 
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> ---
>  fs/xfs/xfs_xattr.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> 
> diff --git a/fs/xfs/xfs_xattr.c b/fs/xfs/xfs_xattr.c
> index c325a28b89a8..10aa1fd39d2b 100644
> --- a/fs/xfs/xfs_xattr.c
> +++ b/fs/xfs/xfs_xattr.c
> @@ -210,7 +210,7 @@ __xfs_xattr_put_listent(
>  		return;
>  	}
>  	offset = context->buffer + context->count;
> -	strncpy(offset, prefix, prefix_len);
> +	memcpy(offset, prefix, prefix_len);
>  	offset += prefix_len;
>  	strncpy(offset, (char *)name, namelen);			/* real name */
>  	offset += namelen;

Looks fine.

Reviewed-by: Dave Chinner <dchinner@redhat.com>

-- 
Dave Chinner
david@fromorbit.com