8272058: 25 Null pointer dereference defect groups in 4 files

Reviewed-by: gziemski, coleenp, dlong

src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2014, 2021, Red Hat Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -160,8 +160,7 @@ int MacroAssembler::pd_patch_instruction_size(address branch, address target) {
     Instruction_aarch64::patch(branch+8, 20, 5, (dest >>= 16) & 0xffff);
     assert(target_addr_for_insn(branch) == target, "should be");
     instructions = 3;
-  } else if (Instruction_aarch64::extract(insn, 31, 22) == 0b1011100101 &&
+  } else if (NativeInstruction::is_ldrw_to_zr(address(&insn))) {
-             Instruction_aarch64::extract(insn, 4, 0) == 0b11111) {
     // nothing to do
     assert(target == 0, "did not expect to relocate target for polling page load");
   } else {
@@ -284,15 +283,19 @@ address MacroAssembler::target_addr_for_insn(address insn_addr, unsigned insn) {
     return address(uint64_t(Instruction_aarch64::extract(insns[0], 20, 5))
                    + (uint64_t(Instruction_aarch64::extract(insns[1], 20, 5)) << 16)
                    + (uint64_t(Instruction_aarch64::extract(insns[2], 20, 5)) << 32));
-  } else if (Instruction_aarch64::extract(insn, 31, 22) == 0b1011100101 &&
-             Instruction_aarch64::extract(insn, 4, 0) == 0b11111) {
-    return 0;
   } else {
     ShouldNotReachHere();
   }
   return address(((uint64_t)insn_addr + (offset << 2)));
 }
 
+address MacroAssembler::target_addr_for_insn_or_null(address insn_addr, unsigned insn) {
+  if (NativeInstruction::is_ldrw_to_zr(address(&insn))) {
+    return 0;
+  }
+  return MacroAssembler::target_addr_for_insn(insn_addr, insn);
+}
+
 void MacroAssembler::safepoint_poll(Label& slow_path, bool at_return, bool acquire, bool in_nmethod) {
   if (acquire) {
     lea(rscratch1, Address(rthread, JavaThread::polling_word_offset()));

src/hotspot/cpu/aarch64/macroAssembler_aarch64.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2014, 2021, Red Hat Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -606,10 +606,15 @@ public:
   static bool uses_implicit_null_check(void* address);
 
   static address target_addr_for_insn(address insn_addr, unsigned insn);
+  static address target_addr_for_insn_or_null(address insn_addr, unsigned insn);
   static address target_addr_for_insn(address insn_addr) {
     unsigned insn = *(unsigned*)insn_addr;
     return target_addr_for_insn(insn_addr, insn);
   }
+  static address target_addr_for_insn_or_null(address insn_addr) {
+    unsigned insn = *(unsigned*)insn_addr;
+    return target_addr_for_insn_or_null(insn_addr, insn);
+  }
 
   // Required platform-specific helpers for Label::patch_instructions.
   // They _shadow_ the declarations in AbstractAssembler, which are undefined.

src/hotspot/cpu/aarch64/nativeInst_aarch64.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2014, 2020, Red Hat Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -315,7 +315,7 @@ void NativeMovRegMem::set_offset(int x) {
 
 void NativeMovRegMem::verify() {
 #ifdef ASSERT
-  address dest = MacroAssembler::target_addr_for_insn(instruction_address());
+  address dest = MacroAssembler::target_addr_for_insn_or_null(instruction_address());
 #endif
 }
 
@@ -329,7 +329,7 @@ void NativeJump::check_verified_entry_alignment(address entry, address verified_
 
 
 address NativeJump::jump_destination() const          {
-  address dest = MacroAssembler::target_addr_for_insn(instruction_address());
+  address dest = MacroAssembler::target_addr_for_insn_or_null(instruction_address());
 
   // We use jump to self as the unresolved address which the inline
   // cache code (and relocs) know about