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Simplify _crypt_extended_init_r, and fix redundant initialization on Win32/Solaris

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Looking at the history of this function, the original implementation had a bug where
it would return from the middle of the function without unlocking the mutex first.
The author attempted to fix this by incrementing the `initialized` flag atomically,
which is not necessary, since the section which modifies the flag is protected by a
mutex.

Coincidentally, at the same time that all this unnecessary 'atomic' machinery was
introduced, the code was also changed so that it didn't return without unlocking the
mutex. So it looks like the bug was fixed by accident.

It's not necessary to declare the flag as `volatile` either, since it is protected
by a mutex.

Further, the 'fixed' implementation was also wrong in another respect: on Windows
and Solaris, the `initialized` flag was not even declared as `static`!! So the
initialization of the static tables for S-boxes, P-boxes, etc. was repeated on
each call to `php_crypt`, completely defeating the purpose of this function.
This commit is contained in:
Alex Dowad 2020-05-27 06:01:22 +02:00
parent 9bd648ba1e
commit 7a9f0cc3d0
3 changed files with 3 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
configure.ac
View File

@ -643,13 +643,6 @@ if test "$ac_cv_func_getaddrinfo" = yes; then
AC_DEFINE(HAVE_GETADDRINFO,1,[Define if you have the getaddrinfo function])
fi
dnl Check for the __sync_fetch_and_add builtin.
AC_CACHE_CHECK([for __sync_fetch_and_add], ac_cv_func_sync_fetch_and_add,
[AC_LINK_IFELSE([AC_LANG_PROGRAM([], [[int x;__sync_fetch_and_add(&x,1);]])],[ac_cv_func_sync_fetch_and_add=yes],[ac_cv_func_sync_fetch_and_add=no])])
if test "$ac_cv_func_sync_fetch_and_add" = yes; then
AC_DEFINE(HAVE_SYNC_FETCH_AND_ADD,1,[Define if you have the __sync_fetch_and_add function])
fi
AC_REPLACE_FUNCS(strlcat strlcpy explicit_bzero getopt)
AC_FUNC_ALLOCA
PHP_TIME_R_TYPE

5
ext/standard/config.m4
View File

@ -388,11 +388,6 @@ if test "$ac_cv_strptime_decl_fails" = "yes"; then
AC_DEFINE([HAVE_STRPTIME_DECL_FAILS], 1, [whether strptime() declaration fails])
fi
dnl
dnl Check for atomic operation API availability in Solaris
dnl
AC_CHECK_HEADERS([atomic.h])
dnl
dnl Check for arc4random on BSD systems
dnl

23
ext/standard/php_crypt_r.c
View File

@ -39,11 +39,6 @@
# include <Wincrypt.h>
#endif
#ifdef HAVE_ATOMIC_H /* Solaris 10 defines atomic API within */
# include <atomic.h>
#else
# include <signal.h>
#endif
#include "php_crypt_r.h"
#include "crypt_freesec.h"
@ -76,29 +71,17 @@ void php_shutdown_crypt_r()
void _crypt_extended_init_r(void)
{
#ifdef PHP_WIN32
LONG volatile initialized = 0;
#elif defined(HAVE_ATOMIC_H) /* Solaris 10 defines atomic API within */
volatile unsigned int initialized = 0;
#else
static volatile sig_atomic_t initialized = 0;
#endif
static int initialized = 0;
#ifdef ZTS
tsrm_mutex_lock(php_crypt_extended_init_lock);
#endif
if (!initialized) {
#ifdef PHP_WIN32
InterlockedIncrement(&initialized);
#elif defined(HAVE_SYNC_FETCH_AND_ADD)
__sync_fetch_and_add(&initialized, 1);
#elif defined(HAVE_ATOMIC_H) /* Solaris 10 defines atomic API within */
membar_producer();
atomic_add_int(&initialized, 1);
#endif
initialized = 1;
_crypt_extended_init();
}
#ifdef ZTS
tsrm_mutex_unlock(php_crypt_extended_init_lock);
#endif