[PATCH v8 1/8] Get rid of __get_task_comm()

[Alejandro Colomar]

Hi Kees,

On Wed, Aug 28, 2024 at 06:48:39AM GMT, Kees Cook wrote:

[...]

> >Thank you for your suggestion. How does the following commit log look
> >to you? Does it meet your expectations?
> >
> >    string: Use ARRAY_SIZE() in strscpy()
> >
> >    We can use ARRAY_SIZE() instead to clarify that they are regular characters.
> >
> >    Co-developed-by: Alejandro Colomar <alx at kernel.org>
> >    Signed-off-by: Alejandro Colomar <alx at kernel.org>
> >    Signed-off-by: Yafang Shao <laoar.shao at gmail.com>
> >
> >diff --git a/arch/um/include/shared/user.h b/arch/um/include/shared/user.h
> >index bbab79c0c074..07216996e3a9 100644
> >--- a/arch/um/include/shared/user.h
> >+++ b/arch/um/include/shared/user.h
> >@@ -14,7 +14,7 @@
> >  * copying too much infrastructure for my taste, so userspace files
> >  * get less checking than kernel files.
> >  */
> >-#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
> >+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]) + __must_be_array(x))
> >
> > /* This is to get size_t and NULL */
> > #ifndef __UM_HOST__
> >@@ -60,7 +60,7 @@ static inline void print_hex_dump(const char *level,
> >const char *prefix_str,
> > extern int in_aton(char *str);
> > extern size_t strlcat(char *, const char *, size_t);
> > extern size_t sized_strscpy(char *, const char *, size_t);
> >-#define strscpy(dst, src)      sized_strscpy(dst, src, sizeof(dst))
> >+#define strscpy(dst, src)      sized_strscpy(dst, src, ARRAY_SIZE(dst))
> 
> Uh, but why? strscpy() copies bytes, not array elements. Using sizeof() is already correct and using ARRAY_SIZE() could lead to unexpectedly small counts (in admittedly odd situations).
> 
> What is the problem you're trying to solve here?

I suggested that here:
<https://lore.kernel.org/all/2jxak5v6dfxlpbxhpm3ey7oup4g2lnr3ueurfbosf5wdo65dk4@srb3hsk72zwq/>

There, you'll find the rationale (and also for avoiding the _pad calls
where not necessary --I ignore if it's necessary here--).

Have a lovely day!
Alex

> 
> -Kees
> 
> -- 
> Kees Cook

-- 
<https://www.alejandro-colomar.es/>
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