[PATCH v3 04/10] stdlib: Improve fortify with clang

[Carlos O'Donell]

On 2/22/24 14:24, Adhemerval Zanella Netto wrote:
> On 20/02/24 19:05, Carlos O'Donell wrote:
>> On 2/8/24 13:46, Adhemerval Zanella wrote:
>>> It improve fortify checks for realpath, ptsname_r, wctomb, mbstowcs,
>>> and wcstombs.  The runtime and compile checks have similar coverage as
>>> with GCC.
>>>
>>
>> Please fix the whitespace change post a v4 of just this patch and I'll
>> give my Reviewed-by.
>>
>> Tested on x86_64 and i686.
>>
>> Tested-by: Carlos O'Donell <carlos@redhat.com>
> 
> Patch below:

LGTM.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>


> --
> It improve fortify checks for realpath, ptsname_r, wctomb, mbstowcs,
> and wcstombs.  The runtime and compile checks have similar coverage as
> with GCC.
> 
> Checked on aarch64, armhf, x86_64, and i686.
> Tested-by: Carlos O'Donell <carlos@redhat.com>
> ---
>  stdlib/bits/stdlib.h | 39 ++++++++++++++++++++++++++++-----------
>  1 file changed, 28 insertions(+), 11 deletions(-)
> 
> diff --git a/stdlib/bits/stdlib.h b/stdlib/bits/stdlib.h
> index 1c7191ba57..1557b862b1 100644
> --- a/stdlib/bits/stdlib.h
> +++ b/stdlib/bits/stdlib.h
> @@ -33,15 +33,22 @@ extern char *__REDIRECT_NTH (__realpath_chk_warn,
>       __warnattr ("second argument of realpath must be either NULL or at "
>  		 "least PATH_MAX bytes long buffer");
>  
> -__fortify_function __wur char *
> -__NTH (realpath (const char *__restrict __name, char *__restrict __resolved))
> +__fortify_function __attribute_overloadable__ __wur char *
> +__NTH (realpath (const char *__restrict __name,
> +		 __fortify_clang_overload_arg (char *, __restrict, __resolved)))
> +#if defined _LIBC_LIMITS_H_ && defined PATH_MAX
> +     __fortify_clang_warning_only_if_bos_lt (PATH_MAX, __resolved,
> +					     "second argument of realpath must be "
> +					     "either NULL or at least PATH_MAX "
> +					     "bytes long buffer")
> +#endif
>  {
>    size_t sz = __glibc_objsize (__resolved);
>  
>    if (sz == (size_t) -1)
>      return __realpath_alias (__name, __resolved);
>  
> -#if defined _LIBC_LIMITS_H_ && defined PATH_MAX
> +#if !__fortify_use_clang && defined _LIBC_LIMITS_H_ && defined PATH_MAX
>    if (__glibc_unsafe_len (PATH_MAX, sizeof (char), sz))
>      return __realpath_chk_warn (__name, __resolved, sz);
>  #endif
> @@ -61,8 +68,13 @@ extern int __REDIRECT_NTH (__ptsname_r_chk_warn,
>       __nonnull ((2)) __warnattr ("ptsname_r called with buflen bigger than "
>  				 "size of buf");
>  
> -__fortify_function int
> -__NTH (ptsname_r (int __fd, char *__buf, size_t __buflen))
> +__fortify_function __attribute_overloadable__ int
> +__NTH (ptsname_r (int __fd,
> +		 __fortify_clang_overload_arg (char *, ,__buf),
> +		 size_t __buflen))
> +     __fortify_clang_warning_only_if_bos_lt (__buflen, __buf,
> +					     "ptsname_r called with buflen "
> +					     "bigger than size of buf")
>  {
>    return __glibc_fortify (ptsname_r, __buflen, sizeof (char),
>  			  __glibc_objsize (__buf),
> @@ -75,8 +87,8 @@ extern int __wctomb_chk (char *__s, wchar_t __wchar, size_t __buflen)
>  extern int __REDIRECT_NTH (__wctomb_alias, (char *__s, wchar_t __wchar),
>  			   wctomb) __wur;
>  
> -__fortify_function __wur int
> -__NTH (wctomb (char *__s, wchar_t __wchar))
> +__fortify_function __attribute_overloadable__ __wur int
> +__NTH (wctomb (__fortify_clang_overload_arg (char *, ,__s), wchar_t __wchar))
>  {
>    /* We would have to include <limits.h> to get a definition of MB_LEN_MAX.
>       But this would only disturb the namespace.  So we define our own
> @@ -113,9 +125,13 @@ extern size_t __REDIRECT_NTH (__mbstowcs_chk_warn,
>       __warnattr ("mbstowcs called with dst buffer smaller than len "
>  		 "* sizeof (wchar_t)");
>  
> -__fortify_function size_t
> -__NTH (mbstowcs (wchar_t *__restrict __dst, const char *__restrict __src,
> +__fortify_function __attribute_overloadable__ size_t
> +__NTH (mbstowcs (__fortify_clang_overload_arg (wchar_t *, __restrict, __dst),
> +		 const char *__restrict __src,
>  		 size_t __len))
> +     __fortify_clang_warning_only_if_bos0_lt2 (__len, __dst, sizeof (wchar_t),
> +					       "mbstowcs called with dst buffer "
> +					       "smaller than len * sizeof (wchar_t)")
>  {
>    if (__builtin_constant_p (__dst == NULL) && __dst == NULL)
>      return __mbstowcs_nulldst (__dst, __src, __len);
> @@ -139,8 +155,9 @@ extern size_t __REDIRECT_NTH (__wcstombs_chk_warn,
>  			       size_t __len, size_t __dstlen), __wcstombs_chk)
>       __warnattr ("wcstombs called with dst buffer smaller than len");
>  
> -__fortify_function size_t
> -__NTH (wcstombs (char *__restrict __dst, const wchar_t *__restrict __src,
> +__fortify_function __attribute_overloadable__ size_t
> +__NTH (wcstombs (__fortify_clang_overload_arg (char *, __restrict, __dst),
> +		 const wchar_t *__restrict __src,
>  		 size_t __len))
>  {
>    return __glibc_fortify (wcstombs, __len, sizeof (char),

-- 
Cheers,
Carlos.