linux-kernel - Re: [PATCH v2] fs/xfs: replace strncpy with memtostr

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Message-ID: <CAH4c4jLCyb3kF0G25GU2JpPVkOXrgMTtMF+NTWgJpXBoEUaA5w@mail.gmail.com>
Date: Thu, 10 Jul 2025 15:56:01 +0530
From: Pranav Tyagi <pranav.tyagi03@...il.com>
To: linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: cem@...nel.org, djwong@...nel.org, skhan@...uxfoundation.org, 
	linux-kernel-mentees@...ts.linux.dev
Subject: Re: [PATCH v2] fs/xfs: replace strncpy with memtostr_pad()

On Fri, Jul 4, 2025 at 3:42 PM Pranav Tyagi <pranav.tyagi03@...il.com> wrote:
>
> Replace the deprecated strncpy() with memtostr_pad(). This also avoids
> the need for separate zeroing using memset(). Mark sb_fname buffer with
> __nonstring as its size is XFSLABEL_MAX and so no terminating NULL for
> sb_fname.
>
> Signed-off-by: Pranav Tyagi <pranav.tyagi03@...il.com>
> ---
>  fs/xfs/libxfs/xfs_format.h | 2 +-
>  fs/xfs/xfs_ioctl.c         | 3 +--
>  2 files changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
> index 9566a7623365..779dac59b1f3 100644
> --- a/fs/xfs/libxfs/xfs_format.h
> +++ b/fs/xfs/libxfs/xfs_format.h
> @@ -112,7 +112,7 @@ typedef struct xfs_sb {
>         uint16_t        sb_sectsize;    /* volume sector size, bytes */
>         uint16_t        sb_inodesize;   /* inode size, bytes */
>         uint16_t        sb_inopblock;   /* inodes per block */
> -       char            sb_fname[XFSLABEL_MAX]; /* file system name */
> +       char            sb_fname[XFSLABEL_MAX] __nonstring; /* file system name */
>         uint8_t         sb_blocklog;    /* log2 of sb_blocksize */
>         uint8_t         sb_sectlog;     /* log2 of sb_sectsize */
>         uint8_t         sb_inodelog;    /* log2 of sb_inodesize */
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index d250f7f74e3b..c3e8c5c1084f 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -990,9 +990,8 @@ xfs_ioc_getlabel(
>         BUILD_BUG_ON(sizeof(sbp->sb_fname) > FSLABEL_MAX);
>
>         /* 1 larger than sb_fname, so this ensures a trailing NUL char */
> -       memset(label, 0, sizeof(label));
>         spin_lock(&mp->m_sb_lock);
> -       strncpy(label, sbp->sb_fname, XFSLABEL_MAX);
> +       memtostr_pad(label, sbp->sb_fname);
>         spin_unlock(&mp->m_sb_lock);
>
>         if (copy_to_user(user_label, label, sizeof(label)))
> --
> 2.49.0
>
Hi,

This is a gentle follow-up on this patch. I would like to
know if there is any update on its state.

Regards
Pranav Tyagi