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

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Message-ID: <20250704101250.24629-1-pranav.tyagi03@gmail.com>
Date: Fri,  4 Jul 2025 15:42:50 +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,
	Pranav Tyagi <pranav.tyagi03@...il.com>
Subject: [PATCH v2] fs/xfs: replace strncpy with memtostr_pad()

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