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

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
---
 arch/microblaze/kernel/prom.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/microblaze/kernel/prom.c b/arch/microblaze/kernel/prom.c
index c5c6186a7e8b..e424c796e297 100644
--- a/arch/microblaze/kernel/prom.c
+++ b/arch/microblaze/kernel/prom.c
@@ -20,7 +20,7 @@ void __init early_init_devtree(void *params)
 
 	early_init_dt_scan(params);
 	if (!strlen(boot_command_line))
-		strlcpy(boot_command_line, cmd_line, COMMAND_LINE_SIZE);
+		strscpy(boot_command_line, cmd_line, COMMAND_LINE_SIZE);
 
 	memblock_allow_resize();

On Tue, 30 May 2023 16:22:02 +0000, Azeem Shaikh wrote:
> 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.
> 
> [...]

Build tested defconfig with GCC 13.1 from:
https://mirrors.edge.kernel.org/pub/tools/crosstool/files/bin/x86_64/13.1.0/

Applied to for-next/hardening, thanks!

[1/1] of/flattree: Replace all non-returning strlcpy with strscpy
      https://git.kernel.org/kees/c/a7969f58df35

-- 
Kees Cook

On Tue, May 30, 2023 at 04:22:02PM +0000, Azeem Shaikh wrote:
> 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
> 
> Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook