From: Nikita Popov <nikita.ppv@gmail.com>
Date: Mon, 11 May 2020 10:43:38 +0000 (+0200)
Subject: Only use ifunc resolvers if __builtin_cpu_supports+init available
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=b111674383fb638830193da672908a3abd5afe4e;p=php

Only use ifunc resolvers if __builtin_cpu_supports+init available

If either of them is not available, the use of zend_cpu_supports()
inside ifunc resolvers may not be safe.
---

diff --git a/Zend/zend_portability.h b/Zend/zend_portability.h
index e1370eecf8..8a278c93f1 100644
--- a/Zend/zend_portability.h
+++ b/Zend/zend_portability.h
@@ -489,7 +489,10 @@ extern "C++" {
 # undef HAVE_FUNC_ATTRIBUTE_IFUNC
 #endif
 
-#if defined(HAVE_FUNC_ATTRIBUTE_IFUNC) && defined(HAVE_FUNC_ATTRIBUTE_TARGET)
+/* Only use ifunc resolvers if we have __builtin_cpu_supports() and __builtin_cpu_init(),
+ * otherwise the use of zend_cpu_supports() may not be safe inside ifunc resolvers. */
+#if defined(HAVE_FUNC_ATTRIBUTE_IFUNC) && defined(HAVE_FUNC_ATTRIBUTE_TARGET) && \
+	defined(PHP_HAVE_BUILTIN_CPU_SUPPORTS) && defined(PHP_HAVE_BUILTIN_CPU_INIT)
 # define ZEND_INTRIN_HAVE_IFUNC_TARGET 1
 #endif