On Thu, Dec 9, 2021 at 8:23 PM Florian Weimer <fweimer@redhat.com> wrote:
>
> * H. J. Lu via Libc-alpha:
>
> > Stop with zero entry point value unless we are tracing shared objects
> > since a zero entry point value in the ELF header indicates there is no
> > associated entry point.  Now we get
> >
> > $ ./elf/ld.so /lib64/libstdc++.so.6.0.29
> > ./elf/ld.so: cannot execute '/lib64/libstdc++.so.6.0.29' without entry point
> > $
> >
> > instead of
> >
> > $ /lib64/ld-linux-x86-64.so.2 /lib64/libstdc++.so.6.0.29
> > Segmentation fault (core dumped)
> > $
> >
> > This fixes [BZ #28453].
>
> Hah.  We recently had a downstream request to fix this.
>
> > +$(objpfx)tst-rtld-run-dso.out: tst-rtld-run-dso.sh $(objpfx)ld.so \
> > +                         $(objpfx)testobj1.so
> > +     $(SHELL) tst-rtld-run-dso.sh $(objpfx)ld.so $(objpfx)testobj1.so \
> > +         '$(test-wrapper-env)' '$(run_program_env)' > $@
> > +     $(evaluate-test)
> > +
>
>
>
> > diff --git a/elf/rtld.c b/elf/rtld.c
> > index 6ce1e07dc0..77bcdf8e29 100644
> > --- a/elf/rtld.c
> > +++ b/elf/rtld.c
> > @@ -1424,6 +1424,14 @@ dl_main (const ElfW(Phdr) *phdr,
> >        implementations which has no real free() function it does not
> >        makes sense to free the old string first.  */
> >        main_map->l_name = (char *) "";
> > +
> > +      /* Stop if there is no associated entry point and we are not
> > +         tracing shared objects.  */
> > +      if (main_map->l_entry == main_map->l_addr
> > +       && state.mode != rtld_mode_trace)
> > +     _dl_fatal_printf("%s: cannot execute '%s' without entry point\n",
> > +                      ld_so_name, _dl_argv[_dl_argc -1]);
>
> Missing space before 1.
>
> Should we say “cannot execute shared object” or “cannot exe[cute a]
> shared library directly”?  execve should fail with ELIBEXEC, and the
> error messages should match.

Fixed.

> Should this check come later, after we have run ELF constructors, to
> maximize backwards compatibility?  ELF constructors might never return.

Fixed.

> Thanks,
> Florian
>

Here is the v3 patch.

-- 
H.J.