8146984: SIGBUS: bool Method::has_method_vptr(const void*)+0xc
Summary: Add address check and use SafeFetchN for Method* vptr access when Method* may be bad pointer.
Reviewed-by: dcubed, mgronlun
--- a/hotspot/src/share/vm/oops/method.cpp Wed Feb 03 14:15:57 2016 +0100
+++ b/hotspot/src/share/vm/oops/method.cpp Wed Feb 03 17:26:36 2016 +0000
@@ -55,6 +55,7 @@
#include "runtime/relocator.hpp"
#include "runtime/sharedRuntime.hpp"
#include "runtime/signature.hpp"
+#include "runtime/stubRoutines.hpp"
#include "utilities/quickSort.hpp"
#include "utilities/xmlstream.hpp"
@@ -2098,23 +2099,29 @@
}
bool Method::has_method_vptr(const void* ptr) {
- Method m;
+ // Use SafeFetch to check if this is a valid pointer first
// This assumes that the vtbl pointer is the first word of a C++ object.
- // This assumption is also in universe.cpp patch_klass_vtble
- void* vtbl2 = dereference_vptr((const void*)&m);
- void* this_vtbl = dereference_vptr(ptr);
- return vtbl2 == this_vtbl;
+ // This assumption is also in universe.cpp patch_klass_vtable
+ intptr_t this_vptr = SafeFetchN((intptr_t*)ptr, intptr_t(1));
+ if (this_vptr == 1) {
+ return false;
+ }
+ Method m;
+ return (intptr_t)dereference_vptr(&m) == this_vptr;
}
// Check that this pointer is valid by checking that the vtbl pointer matches
bool Method::is_valid_method() const {
if (this == NULL) {
return false;
- } else if (!is_metaspace_object()) {
+ }
+
+ // Quick sanity check on pointer.
+ if ((intptr_t(this) & (wordSize-1)) != 0) {
return false;
- } else {
- return has_method_vptr((const void*)this);
}
+
+ return has_method_vptr(this);
}
#ifndef PRODUCT