[PATCH] gold: ensure file_counts_lock is initialized before using

[H.J. Lu]

On Thu, Oct 29, 2020 at 7:39 PM Nick Gasson via Binutils
<binutils@sourceware.org> wrote:
>
> > Since upgrading to binutils 2.35 I've been experiencing random memory
> > corruption related crashes with ld.gold --threads. It's caused by
> > multiple threads concurrently pushing elements onto the shared
> > std::vector in File_read::record_file_read(). This vector is supposed to
> > be protected by file_counts_lock, but that is initialized lazily and
> > might be NULL when File_read::open() is called, in which case
> > Hold_optional_lock silently skips locking it.
> >
>
> Is anyone able review this patch? This bug is quite easy to reproduce
> with e.g. the binutils in Debian unstable:
>
> $ gcc -fuse-ld=gold -Wl,--threads test.c
> malloc(): invalid next size (unsorted)
> collect2: fatal error: ld terminated with signal 6 [Aborted], core dumped
> compilation terminated.
> $ gcc -fuse-ld=gold -Wl,--threads test.c
> $ gcc -fuse-ld=gold -Wl,--threads test.c
> double free or corruption (out)
> collect2: fatal error: ld terminated with signal 11 [Segmentation fault], core dumped
> compilation terminated.
>
> > Fix by calling the initialize() method before attempting to acquire the
> > lock, the same as other places that use file_counts_lock.
> >
> >        * fileread.cc (File_read::open): Ensure file_counts_lock is
> >        initialized.
> > ---
> >  gold/fileread.cc | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/gold/fileread.cc b/gold/fileread.cc
> > index f5ca719360d6..0b5228e2afd4 100644
> > --- a/gold/fileread.cc
> > +++ b/gold/fileread.cc
> > @@ -212,6 +212,7 @@ File_read::open(const Task* task, const std::string& name)
> >        gold_debug(DEBUG_FILES, "Attempt to open %s succeeded",
> >                this->name_.c_str());
> >        this->token_.add_writer(task);
> > +      file_counts_initialize_lock.initialize();
> >        Hold_optional_lock hl(file_counts_lock);
> >        record_file_read(this->name_);
> >      }
>

Please open a gold bug and update your patch with a testcase.
BTW, does it fix

https://sourceware.org/bugzilla/show_bug.cgi?id=26200

Thanks.

-- 
H.J.