Hi,

On Wed, Mar 20, 2024 at 12:56 AM Helge Deller [off-list ref] wrote:

On 3/19/24 00:46, Justin Stitt wrote:

quoted

strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

Let's use the new 2-argument strscpy() which guarantees NUL-termination
on the destination buffer while also simplifying the syntax. Note that
strscpy() will not NUL-pad the destination buffer like strncpy() does.

However, the NUL-padding behavior of strncpy() is not required since
fbdev is already NUL-allocated from au1200fb_drv_probe() ->
frameuffer_alloc(), rendering any additional NUL-padding redundant.
|     p = kzalloc(fb_info_size + size, GFP_KERNEL);

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Note: build-tested only.

Found with: $ rg "strncpy\("
---
  drivers/video/fbdev/au1200fb.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/au1200fb.c b/drivers/video/fbdev/au1200fb.c
index 6f20efc663d7..e718fea63662 100644
--- a/drivers/video/fbdev/au1200fb.c
+++ b/drivers/video/fbdev/au1200fb.c

@@ -1557,7 +1557,7 @@ static int au1200fb_init_fbinfo(struct au1200fb_device *fbdev)
              return ret;
      }

-     strncpy(fbi->fix.id, "AU1200", sizeof(fbi->fix.id));
+     strscpy(fbi->fix.id, "AU1200");

I wonder if you really build-tested this, as this driver is for the mips architecture...
And I don't see a strscpy() function which takes just 2 arguments.
But I might be wrong....

I did build successfully :thumbs_up:

Commit e6584c3964f2f ("string: Allow 2-argument strscpy()") introduced
this new strscpy() form; it is present in string.h on Linus' tree.

Helge

Thanks
Justin