8300821: UB: Applying non-zero offset to non-null pointer 0xfffffffffffffffe produced null pointer

Reviewed-by: kvn, thartmann

Author: tobiasholenstein

src/hotspot/share/asm/codeBuffer.cpp

@@ -523,7 +523,7 @@ void CodeBuffer::finalize_oop_references(const methodHandle& mh) {
   for (int n = (int) SECT_FIRST; n < (int) SECT_LIMIT; n++) {
     // pull code out of each section
     CodeSection* cs = code_section(n);
-    if (cs->is_empty())  continue;  // skip trivial section
+    if (cs->is_empty() || !cs->has_locs()) continue;  // skip trivial section
     RelocIterator iter(cs);
     while (iter.next()) {
       if (iter.type() == relocInfo::metadata_type) {
@@ -791,7 +791,7 @@ void CodeBuffer::relocate_code_to(CodeBuffer* dest) const {
   for (int n = (int) SECT_FIRST; n < (int)SECT_LIMIT; n++) {
     // pull code out of each section
     const CodeSection* cs = code_section(n);
-    if (cs->is_empty()) continue;  // skip trivial section
+    if (cs->is_empty() || !cs->has_locs()) continue;  // skip trivial section
     CodeSection* dest_cs = dest->code_section(n);
     { // Repair the pc relative information in the code after the move
       RelocIterator iter(dest_cs);

src/hotspot/share/code/relocInfo.cpp

@@ -149,7 +149,8 @@ void RelocIterator::initialize(CompiledMethod* nm, address begin, address limit)
 
 RelocIterator::RelocIterator(CodeSection* cs, address begin, address limit) {
   initialize_misc();
-
+  assert((cs->locs_start() != nullptr) && (cs->locs_end() != nullptr) ||
+         (cs->locs_start() == nullptr) && (cs->locs_end() == nullptr), "valid start and end pointer");
   _current = cs->locs_start()-1;
   _end     = cs->locs_end();
   _addr    = cs->start();