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Fix OPcache memory protection race under ZTS #23081

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Fix OPcache memory protection race under ZTS #23081

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4b95c0c
Fix OPcache memory protection race under ZTS
realFlowControl Aug 6, 2026
400b479
Fix Windows OPcache build
realFlowControl Aug 6, 2026
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3 changes: 3 additions & 0 deletions ext/opcache/ZendAccelerator.h
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Original file line number Diff line number Diff line change
Expand Up @@ -199,6 +199,9 @@ typedef struct _zend_accel_globals {
bool counted; /* the process uses shared memory */
bool enabled;
bool locked; /* thread obtained exclusive lock */
#ifdef ZTS
uint32_t unprotect_depth;
#endif
bool accelerator_enabled; /* accelerator enabled for current request */
bool pcre_reseted;
zend_accel_directives accel_directives;
Expand Down
44 changes: 37 additions & 7 deletions ext/opcache/zend_shared_alloc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,11 @@ static const char *g_shared_model;
/* pointer to globals allocated in SHM and shared across processes */
ZEND_EXT_API zend_smm_shared_globals *smm_shared_globals;

#ifdef ZTS
static MUTEX_T zts_protect_lock;
static uint32_t zts_unprotected_threads;
#endif

#ifndef ZEND_WIN32
#ifdef ZTS
static MUTEX_T zts_lock;
Expand Down Expand Up @@ -184,6 +189,11 @@ int zend_shared_alloc_startup(size_t requested_size, size_t reserved_size)
int res = ALLOC_FAILURE;
int i;

#ifdef ZTS
zts_protect_lock = tsrm_mutex_alloc();
zts_unprotected_threads = 0;
#endif

/* shared_free must be valid before we call zend_shared_alloc()
* - make it temporarily point to a local variable
*/
Expand Down Expand Up @@ -338,6 +348,9 @@ void zend_shared_alloc_shutdown(void)
tsrm_mutex_free(zts_lock);
# endif
#endif
#ifdef ZTS
tsrm_mutex_free(zts_protect_lock);
#endif
}

static size_t zend_shared_alloc_get_largest_free_block(void)
Expand Down Expand Up @@ -625,25 +638,37 @@ const char *zend_accel_get_shared_model(void)

void zend_accel_shared_protect(bool protected)
{
#ifdef HAVE_MPROTECT
#if defined(HAVE_MPROTECT) || defined(ZEND_WIN32)
int i;

if (!smm_shared_globals) {
return;
}

#ifdef ZTS

@arnaud-lb arnaud-lb Aug 7, 2026

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Please indent nested preprocessor directives:

Suggested change
#ifdef ZTS
# ifdef ZTS

/* Memory protection is process-wide, so overlapping writers must be tracked across threads. */
tsrm_mutex_lock(zts_protect_lock);
if (protected) {
if (ZCG(unprotect_depth) && --ZCG(unprotect_depth) == 0) {
ZEND_ASSERT(zts_unprotected_threads > 0);
zts_unprotected_threads--;
}
if (zts_unprotected_threads) {
tsrm_mutex_unlock(zts_protect_lock);
return;
}
} else if (ZCG(unprotect_depth)++ == 0) {
zts_unprotected_threads++;
}
#endif

#ifdef HAVE_MPROTECT
const int mode = protected ? PROT_READ : PROT_READ|PROT_WRITE;

for (i = 0; i < ZSMMG(shared_segments_count); i++) {
mprotect(ZSMMG(shared_segments)[i]->p, ZSMMG(shared_segments)[i]->end, mode);
}
#elif defined(ZEND_WIN32)
int i;

if (!smm_shared_globals) {
return;
}

const int mode = protected ? PAGE_READONLY : PAGE_READWRITE;

for (i = 0; i < ZSMMG(shared_segments_count); i++) {
Expand All @@ -653,6 +678,11 @@ void zend_accel_shared_protect(bool protected)
}
}
#endif

#ifdef ZTS

@arnaud-lb arnaud-lb Aug 7, 2026

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Ditto

tsrm_mutex_unlock(zts_protect_lock);
#endif
#endif
}

bool zend_accel_in_shm(void *ptr)
Expand Down
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