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  1. JDK
  2. JDK-8247818

GCC 10 warning stringop-overflow with symbol code

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    Details

    • Type: Bug
    • Status: Resolved
    • Priority: P4
    • Resolution: Fixed
    • Affects Version/s: 16
    • Fix Version/s: 16
    • Component/s: hotspot
    • Environment:

      gcc 10

    • Subcomponent:
    • Resolved In Build:
      b06

      Description

      On 18/06/2020 8:46 am, Koichi Sakata wrote:
      Hi all,

      I tried to build OpenJDK fastdebug with GCC 10.1 on Ubuntu 18.04, but I saw some compiler warnings as follows:

      In file included from
      /home/jyukutyo/code/jdk/src/hotspot/share/classfile/systemDictionary.hpp:31,
                        from
      /home/jyukutyo/code/jdk/src/hotspot/share/classfile/javaClasses.hpp:28,
                        from
      /home/jyukutyo/code/jdk/src/hotspot/share/precompiled/precompiled.hpp:35:
      In member function 'void Symbol::byte_at_put(int, u1)',
           inlined from 'Symbol::Symbol(const u1*, int, int)' at
      /home/jyukutyo/code/jdk/src/hotspot/share/oops/symbol.cpp:55:16:
      /home/jyukutyo/code/jdk/src/hotspot/share/oops/symbol.hpp:130:18: error:
      writing 1 byte into a region of size 0 [-Werror=stringop-overflow=]
         130 | _body[index] = value;
             | ~~~~~~~~~~~~~^~~~~~~

      I can resolve them with the following patch. I believe it fixes those potential bugs, so I'd like to contribute it.
      (Our company has signed OCA.)

      Thanks,
      Koichi

      ===== PATCH =====
      diff -r 20d92fe3ac52 src/hotspot/share/oops/symbol.cpp
      --- a/src/hotspot/share/oops/symbol.cpp Tue Jun 16 03:16:41 2020 +0000
      +++ b/src/hotspot/share/oops/symbol.cpp Thu Jun 18 07:08:50 2020 +0900
      @@ -50,9 +50,10 @@
       Symbol::Symbol(const u1* name, int length, int refcount) {
         _hash_and_refcount = pack_hash_and_refcount((short)os::random(), refcount);
         _length = length;
      - _body[0] = 0; // in case length == 0
      - for (int i = 0; i < length; i++) {
      - byte_at_put(i, name[i]);
      + if (length == 0) {
      + _body[0] = 0;
      + } else {
      + memcpy(_body, name, length);
         }
       }

      diff -r 20d92fe3ac52 src/hotspot/share/oops/symbol.hpp
      --- a/src/hotspot/share/oops/symbol.hpp Tue Jun 16 03:16:41 2020 +0000
      +++ b/src/hotspot/share/oops/symbol.hpp Thu Jun 18 07:08:50 2020 +0900
      @@ -125,11 +125,6 @@
           return (int)heap_word_size(byte_size(length));
         }

      - void byte_at_put(int index, u1 value) {
      - assert(index >=0 && index < length(), "symbol index overflow");
      - _body[index] = value;
      - }
      -
         Symbol(const u1* name, int length, int refcount);
         void* operator new(size_t size, int len) throw();
         void* operator new(size_t size, int len, Arena* arena) throw();

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              Assignee:
              iklam Ioi Lam
              Reporter:
              dholmes David Holmes
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                Created:
                Updated:
                Resolved: