befs: Replace all non-returning strlcpy with strscpy

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated.
In an effort to remove strlcpy() completely, replace
strlcpy() here with strscpy().
No return values were used, so direct replacement is safe.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] KSPP#89

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230509014136.2095900-1-azeemshaikh38@gmail.com

Author: azeemshaikh38

fs/befs/btree.c

@@ -500,7 +500,7 @@ befs_btree_read(struct super_block *sb, const befs_data_stream *ds,
 		goto error_alloc;
 	}
 
-	strlcpy(keybuf, keystart, keylen + 1);
+	strscpy(keybuf, keystart, keylen + 1);
 	*value = fs64_to_cpu(sb, valarray[cur_key]);
 	*keysize = keylen;
 

fs/befs/linuxvfs.c

@@ -374,7 +374,7 @@ static struct inode *befs_iget(struct super_block *sb, unsigned long ino)
 	if (S_ISLNK(inode->i_mode) && !(befs_ino->i_flags & BEFS_LONG_SYMLINK)){
 		inode->i_size = 0;
 		inode->i_blocks = befs_sb->block_size / VFS_BLOCK_SIZE;
-		strlcpy(befs_ino->i_data.symlink, raw_inode->data.symlink,
+		strscpy(befs_ino->i_data.symlink, raw_inode->data.symlink,
 			BEFS_SYMLINK_LEN);
 	} else {
 		int num_blks;