[PATCH] D48806: [asan] Fix deadlock issue on FreeBSD, caused by use of .preinit_array in rL325240

[Fangrui Song via Phabricator via llvm-commits]

MaskRay updated this revision to Diff 153651.
MaskRay added a comment.

Special case xray to use unsafe .preinit_array


Repository:
  rCRT Compiler Runtime

https://reviews.llvm.org/D48806

Files:
  lib/sanitizer_common/sanitizer_internal_defs.h
  lib/xray/xray_init.cc


Index: lib/xray/xray_init.cc
===================================================================
--- lib/xray/xray_init.cc
+++ lib/xray/xray_init.cc
@@ -84,7 +84,13 @@
 #endif
 }
 
-#if !defined(XRAY_NO_PREINIT) && SANITIZER_CAN_USE_PREINIT_ARRAY
+// FIXME: Make check-xray tests work on FreeBSD without
+// SANITIZER_CAN_USE_PREINIT_ARRAY.
+// See sanitizer_internal_defs.h where the macro is defined.
+// Calling unresolved PLT functions in .preinit_array can lead to deadlock on
+// FreeBSD but here it seems benign.
+#if !defined(XRAY_NO_PREINIT) &&                                               \
+    (SANITIZER_CAN_USE_PREINIT_ARRAY || SANITIZER_FREEBSD)
 // Only add the preinit array initialization if the sanitizers can.
 __attribute__((section(".preinit_array"),
                used)) void (*__local_xray_preinit)(void) = __xray_init;
Index: lib/sanitizer_common/sanitizer_internal_defs.h
===================================================================
--- lib/sanitizer_common/sanitizer_internal_defs.h
+++ lib/sanitizer_common/sanitizer_internal_defs.h
@@ -98,11 +98,16 @@
 
 // We can use .preinit_array section on Linux to call sanitizer initialization
 // functions very early in the process startup (unless PIC macro is defined).
+//
+// On FreeBSD, .preinit_array functions are called with rtld_bind_lock writer
+// lock held. It will lead to dead lock if unresolved PLT functions (which helds
+// rtld_bind_lock reader lock) are called inside .preinit_array functions.
+//
 // FIXME: do we have anything like this on Mac?
 #ifndef SANITIZER_CAN_USE_PREINIT_ARRAY
-#if ((SANITIZER_LINUX && !SANITIZER_ANDROID) || \
-  SANITIZER_FREEBSD || SANITIZER_OPENBSD) && !defined(PIC)
-# define SANITIZER_CAN_USE_PREINIT_ARRAY 1
+#if ((SANITIZER_LINUX && !SANITIZER_ANDROID) || SANITIZER_OPENBSD) && \
+    !defined(PIC)
+#define SANITIZER_CAN_USE_PREINIT_ARRAY 1
 // Before Solaris 11.4, .preinit_array is fully supported only with GNU ld.
 // FIXME: Check for those conditions.
 #elif SANITIZER_SOLARIS && !defined(PIC)


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