fbdev: fsl-diu-fb: replace deprecated strncpy with strscpy_pad

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

A better alternative is strscpy() as it guarantees NUL-termination on
the destination buffer.

Since we are eventually copying over to userspace, let's ensure we
NUL-pad the destination buffer by using the pad variant of strscpy.
- core/fb_chrdev.c:
234 |	err = copy_to_user(&fix32->id, &fix->id, sizeof(fix32->id));

Furthermore, we can use the new 2-argument variants of strscpy() and
strscpy_pad() introduced by Commit e6584c3964f2f ("string: Allow
2-argument strscpy()") to simplify the syntax even more.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/drivers/video/fbdev/fsl-diu-fb.c b/drivers/video/fbdev/fsl-diu-fb.c
index 0191141657fd92d9fc13d49045617aa2947fa971..ea37a60da10c42c88770482e99a9566ee90e4b0b 100644 (file)
--- a/drivers/video/fbdev/fsl-diu-fb.c
+++ b/drivers/video/fbdev/fsl-diu-fb.c
@@ -787,7 +787,7 @@ static void set_fix(struct fb_info *info)
        struct fb_var_screeninfo *var = &info->var;
        struct mfb_info *mfbi = info->par;
 
-       strncpy(fix->id, mfbi->id, sizeof(fix->id));
+       strscpy_pad(fix->id, mfbi->id);
        fix->line_length = var->xres_virtual * var->bits_per_pixel / 8;
        fix->type = FB_TYPE_PACKED_PIXELS;
        fix->accel = FB_ACCEL_NONE;