Merge "[dev.typeparams] all: merge master (46fd547) into dev.typeparams" into dev.typeparamsdev.typeparams

1 files changed, 20 insertions, 0 deletions

diff --git a/src/runtime/cgo/gcc_traceback.c b/src/runtime/cgo/gcc_traceback.c
index d86331c583..6e9470c43c 100644
--- a/src/runtime/cgo/gcc_traceback.c
+++ b/src/runtime/cgo/gcc_traceback.c
@@ -7,6 +7,14 @@
 #include <stdint.h>
 #include "libcgo.h"
 
+#ifndef __has_feature
+#define __has_feature(x) 0
+#endif
+
+#if __has_feature(memory_sanitizer)
+#include <sanitizer/msan_interface.h>
+#endif
+
 // Call the user's traceback function and then call sigtramp.
 // The runtime signal handler will jump to this code.
 // We do it this way so that the user's traceback function will be called
@@ -19,6 +27,18 @@ x_cgo_callers(uintptr_t sig, void *info, void *context, void (*cgoTraceback)(str
 	arg.SigContext = (uintptr_t)(context);
 	arg.Buf = cgoCallers;
 	arg.Max = 32; // must match len(runtime.cgoCallers)
+
+#if __has_feature(memory_sanitizer)
+        // This function is called directly from the signal handler.
+        // The arguments are passed in registers, so whether msan
+        // considers cgoCallers to be initialized depends on whether
+        // it considers the appropriate register to be initialized.
+        // That can cause false reports in rare cases.
+        // Explicitly unpoison the memory to avoid that.
+        // See issue #47543 for more details.
+        __msan_unpoison(&arg, sizeof arg);
+#endif
+
 	(*cgoTraceback)(&arg);
 	sigtramp(sig, info, context);
 }