ARM: 9300/1: 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 [1].  In
an effort to remove strlcpy() completely [2], 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] https://github.com/KSPP/linux/issues/89

[ardb: submitting to the patch tracker on behalf of Azeem]
Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

arch/arm/kernel/atags_parse.c

@@ -127,7 +127,7 @@ static int __init parse_tag_cmdline(const struct tag *tag)
 #elif defined(CONFIG_CMDLINE_FORCE)
 	pr_warn("Ignoring tag cmdline (using the default kernel command line)\n");
 #else
-	strlcpy(default_command_line, tag->u.cmdline.cmdline,
+	strscpy(default_command_line, tag->u.cmdline.cmdline,
 		COMMAND_LINE_SIZE);
 #endif
 	return 0;
@@ -224,7 +224,7 @@ setup_machine_tags(void *atags_vaddr, unsigned int machine_nr)
 	}
 
 	/* parse_early_param needs a boot_command_line */
-	strlcpy(boot_command_line, from, COMMAND_LINE_SIZE);
+	strscpy(boot_command_line, from, COMMAND_LINE_SIZE);
 
 	return mdesc;
 }

arch/arm/kernel/setup.c

@@ -1142,7 +1142,7 @@ void __init setup_arch(char **cmdline_p)
 	setup_initial_init_mm(_text, _etext, _edata, _end);
 
 	/* populate cmd_line too for later use, preserving boot_command_line */
-	strlcpy(cmd_line, boot_command_line, COMMAND_LINE_SIZE);
+	strscpy(cmd_line, boot_command_line, COMMAND_LINE_SIZE);
 	*cmdline_p = cmd_line;
 
 	early_fixmap_init();

arch/arm/kernel/vdso.c

@@ -135,7 +135,7 @@ static Elf32_Sym * __init find_symbol(struct elfinfo *lib, const char *symname)
 
 		if (lib->dynsym[i].st_name == 0)
 			continue;
-		strlcpy(name, lib->dynstr + lib->dynsym[i].st_name,
+		strscpy(name, lib->dynstr + lib->dynsym[i].st_name,
 			MAX_SYMNAME);
 		c = strchr(name, '@');
 		if (c)