[Bug malloc/12155] MALLOC_MMAP_THRESHOLD_ and MALLOC_MMAP_MAX_ have different effect for setgid than for setuid programs

["neleai at seznam dot cz" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=12155

Ondrej Bilka <neleai at seznam dot cz> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |neleai at seznam dot cz

--- Comment #6 from Ondrej Bilka <neleai at seznam dot cz> ---
Weird as these variables are handled by malloc/arena.c:

 if (! __builtin_expect (__libc_enable_secure, 0))
                {
                  if (memcmp (envline, "TRIM_THRESHOLD_", 15) == 0)
                    __libc_mallopt(M_TRIM_THRESHOLD, atoi(&envline[16]));
                  else if (memcmp (envline, "MMAP_THRESHOLD_", 15) == 0)
                    __libc_mallopt(M_MMAP_THRESHOLD, atoi(&envline[16]));
                }

and __libc_enable_secure is defined as

  if (__libc_enable_secure_decided == 0)
    __libc_enable_secure = (__geteuid () != __getuid ()
                            || __getegid () != __getgid ());

A simple program shows that this is enabled in both cases.

extern int __libc_enable_secure;
int main ()
{
  printf ("%i %i %i %i", getuid(), geteuid(), getgid(), getegid());
  printf (" %i", __libc_enable_secure);
}

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