[PATCH] xtensa: use strscpy to copy strings

[PATCH] xtensa: use strscpy to copy strings

[Jason Wang]

The strlcpy should not be used because it doesn't limit the source
length. So that it will lead some potential bugs.

But the strscpy doesn't require reading memory from the src string
beyond the specified "count" bytes, and since the return value is
easier to error-check than strlcpy()'s. In addition, the implementation
is robust to the string changing out from underneath it, unlike the
current strlcpy() implementation.

Thus, replace strlcpy with strscpy.

Signed-off-by: Jason Wang <wangborong@cdjrlc.com>
---
 arch/xtensa/kernel/setup.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/xtensa/kernel/setup.c b/arch/xtensa/kernel/setup.c
index 8db20cfb44ab..3f1842891482 100644
--- a/arch/xtensa/kernel/setup.c
+++ b/arch/xtensa/kernel/setup.c
@@ -140,7 +140,7 @@ __tagtable(BP_TAG_FDT, parse_tag_fdt);
 
 static int __init parse_tag_cmdline(const bp_tag_t* tag)
 {
-	strlcpy(command_line, (char *)(tag->data), COMMAND_LINE_SIZE);
+	strscpy(command_line, (char *)(tag->data), COMMAND_LINE_SIZE);
 	return 0;
 }
 
@@ -230,7 +230,7 @@ void __init early_init_devtree(void *params)
 	of_scan_flat_dt(xtensa_dt_io_area, NULL);
 
 	if (!command_line[0])
-		strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
+		strscpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
 }
 
 #endif /* CONFIG_USE_OF */
@@ -260,7 +260,7 @@ void __init init_arch(bp_tag_t *bp_start)
 
 #ifdef CONFIG_CMDLINE_BOOL
 	if (!command_line[0])
-		strlcpy(command_line, default_command_line, COMMAND_LINE_SIZE);
+		strscpy(command_line, default_command_line, COMMAND_LINE_SIZE);
 #endif
 
 	/* Early hook for platforms */
@@ -289,7 +289,7 @@ void __init setup_arch(char **cmdline_p)
 
 	*cmdline_p = command_line;
 	platform_setup(cmdline_p);
-	strlcpy(boot_command_line, *cmdline_p, COMMAND_LINE_SIZE);
+	strscpy(boot_command_line, *cmdline_p, COMMAND_LINE_SIZE);
 
 	/* Reserve some memory regions */
 
-- 
2.34.1

Re: [PATCH] xtensa: use strscpy to copy strings

[Max Filippov]

On Mon, Dec 20, 2021 at 12:50 AM Jason Wang <wangborong@cdjrlc.com> wrote:
>
> The strlcpy should not be used because it doesn't limit the source
> length. So that it will lead some potential bugs.
>
> But the strscpy doesn't require reading memory from the src string
> beyond the specified "count" bytes, and since the return value is
> easier to error-check than strlcpy()'s. In addition, the implementation
> is robust to the string changing out from underneath it, unlike the
> current strlcpy() implementation.
>
> Thus, replace strlcpy with strscpy.
>
> Signed-off-by: Jason Wang <wangborong@cdjrlc.com>
> ---
>  arch/xtensa/kernel/setup.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)

Applied to my xtensa tree. Thanks.

-- Max