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Re: running valgrind with vim

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  • Ali Akcaagac
    ... I know what valgrind is. mfg, Ali Akcaagac --~--~---------~--~----~------------~-------~--~----~ You received this message from the vim_dev maillist. For
    Message 1 of 4 , Aug 5, 2007
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      On Sat, 2007-08-04 at 22:57 -0400, Fuzzy Logic wrote:
      > Valgrind validates that every bit of memory accessed is properly
      > initialized. It runs the program under a virtual CPU. They are errors,
      > but they could be because of optimizations created by the compiler.

      I know what valgrind is.

      mfg,

      Ali Akcaagac


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    • Bram Moolenaar
      ... Thanks for digging into this. I spotted a few other places where p_extra may point to text that is not NUL terminated and where utfc_ptr2len() may not work
      Message 2 of 4 , Aug 5, 2007
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        Dominique Pelle wrote:

        > > > Hi,
        > > >
        > > > Valgrind memory checker finds several errors in vim-7.1 (patches 1-50)
        > > > when built with --enable-multibyte:
        > > >
        > > > $ ./configure --enable-multibyte
        > > > $ make CFLAGS="-O0 -g"
        > > > $ cd src/testdir
        > > > $ valgrind ../vim -u unix.vim -U NONE --noplugin -s dotest.in
        > > > test45.in 2> valgrind-test45.txt
        >
        > ...
        >
        > > It's a lot of work to check out the warnings, so please make sure there
        > > are no false warnings.
        >
        >
        > I believe I have a patch to fix errors reported by valgrind in test case 45
        > but please review it.
        >
        > Error was:
        >
        > ==14428== Conditional jump or move depends on uninitialised value(s)
        > ==14428== at 0x80FDD10: utfc_ptr2len (mbyte.c:1676)
        > ==14428== by 0x813EB6B: win_line (screen.c:3586)
        > ==14428== by 0x813BBF0: win_update (screen.c:1760)
        > ==14428== by 0x8139FFE: update_screen (screen.c:522)
        > ==14428== by 0x80CD1CF: main_loop (main.c:1088)
        > ==14428== by 0x80CCF72: main (main.c:939)
        > etc.
        >
        > Variable p_extra at screen.c:3586 was initialized by fill_foldcolumn()
        > with 'foldcolumn' spaces (3 spaces in test case 45). 'p_extra' pointer
        > is actually in this case the local 'extra' array. The rest of 'p_extra'
        > buffer is uninitialized. vim_line() then loops on those 3 spaces but
        > accesses the next characters inside utfc_ptr2len() when multi_byte
        > is enabled, hence causing valgrind to complain when displaying
        > the last space.
        >
        > Bug can be simply triggered when doing ":set foldcolumn" and when
        > vim was built 'multi_byte'. The following command is enough to trigger
        > an error with valgrind:
        >
        > $ vim -u NONE -c 'set foldcolumn=4' 2> valgrind.log
        >
        > I attach the patch to fix the problem. It basically adds NUL character
        > at the end of 'foldcolumn' spaces when. This patch actually fixes all errors
        > reported by valgrind in test case 45.
        >
        > Without patch, bahavior of calling utfc_ptr2len() at line screen.c:3586
        > may be undetermined. It's also slower since it may need to call
        > utf_ptr2len() whereas with patch, function utfc_ptr2len() returns
        > immediately at mbyte.c:1676.

        Thanks for digging into this.

        I spotted a few other places where p_extra may point to text that is not
        NUL terminated and where utfc_ptr2len() may not work correctly. That
        won't give an uninitialized read error, but it may still be wrong.

        --
        From "know your smileys":
        =):-) Uncle Sam

        /// Bram Moolenaar -- Bram@... -- http://www.Moolenaar.net \\\
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