linux-kernel - [PATCH v3] btrfs: replace deprecated strcpy with strscpy

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Message-ID: <20250620014344.27589-1-listout@listout.xyz>
Date: Fri, 20 Jun 2025 07:13:44 +0530
From: Brahmajit Das <listout@...tout.xyz>
To: linux-hardening@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-btrfs@...r.kernel.org
Cc: clm@...com,
	josef@...icpanda.com,
	dsterba@...e.com,
	kees@...nel.org,
	ailiop@...e.com,
	Mark Harmstone <mark@...mstone.com>
Subject: [PATCH v3] btrfs: replace deprecated strcpy with strscpy

strcpy is deprecated due to lack of bounds checking. This patch replaces
strcpy with strscpy, the recommended alternative for null terminated
strings, to follow best practices.

There are instances where strscpy cannot be used such as where both the
source and destination are character pointers. In that instance we can
use sysfs_emit or a memcpy.

Update in v2: using sysfs_emit instead of scnprintf
Update in v3: Removed string.h in xattr, since we are not using any
fucntions from string.h and fixed length in memcpy in volumes.c

No functional changes intended.

Link: https://github.com/KSPP/linux/issues/88

Suggested-by: Anthony Iliopoulos <ailiop@...e.com>
Suggested-by: Mark Harmstone <mark@...mstone.com>
Signed-off-by: Brahmajit Das <listout@...tout.xyz>
---
 fs/btrfs/ioctl.c   | 2 +-
 fs/btrfs/send.c    | 2 +-
 fs/btrfs/volumes.c | 2 +-
 fs/btrfs/xattr.c   | 3 +--
 4 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 913acef3f0a9..203f309f00b1 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4200,7 +4200,7 @@ static int btrfs_ioctl_set_fslabel(struct file *file, void __user *arg)
 	}
 
 	spin_lock(&fs_info->super_lock);
-	strcpy(super_block->label, label);
+	strscpy(super_block->label, label);
 	spin_unlock(&fs_info->super_lock);
 	ret = btrfs_commit_transaction(trans);
 
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 2891ec4056c6..66ee9e1b1e96 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -758,7 +758,7 @@ static int send_header(struct send_ctx *sctx)
 {
 	struct btrfs_stream_header hdr;
 
-	strcpy(hdr.magic, BTRFS_SEND_STREAM_MAGIC);
+	strscpy(hdr.magic, BTRFS_SEND_STREAM_MAGIC);
 	hdr.version = cpu_to_le32(sctx->proto);
 	return write_buf(sctx->send_filp, &hdr, sizeof(hdr),
 					&sctx->send_off);
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 89835071cfea..86a898bb2fbb 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -215,7 +215,7 @@ void btrfs_describe_block_groups(u64 bg_flags, char *buf, u32 size_buf)
 	u32 size_bp = size_buf;
 
 	if (!flags) {
-		strcpy(bp, "NONE");
+		memcpy(bp, "NONE", 5);
 		return;
 	}
 
diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index 3e0edbcf73e1..49fd8a49584a 100644
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -516,8 +516,7 @@ static int btrfs_initxattrs(struct inode *inode,
 			ret = -ENOMEM;
 			break;
 		}
-		strcpy(name, XATTR_SECURITY_PREFIX);
-		strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
+		sysfs_emit(name, "%s%s", XATTR_SECURITY_PREFIX, xattr->name);
 
 		if (strcmp(name, XATTR_NAME_CAPS) == 0)
 			clear_bit(BTRFS_INODE_NO_CAP_XATTR, &BTRFS_I(inode)->runtime_flags);
-- 
2.50.0