Re: [PATCH] elf: Replace tst-p_alignmod1-editX with a python script

["H.J. Lu" <hjl.tools@gmail.com>]

On Wed, Jan 26, 2022 at 7:54 AM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 26/01/2022 12:46, H.J. Lu wrote:
> > On Wed, Jan 26, 2022 at 7:45 AM Adhemerval Zanella
> > <adhemerval.zanella@linaro.org> wrote:
> >>
> >>
> >>
> >> On 26/01/2022 12:35, H.J. Lu wrote:
> >>> On Wed, Jan 26, 2022 at 4:10 AM Adhemerval Zanella
> >>> <adhemerval.zanella@linaro.org> wrote:
> >>>>
> >>>>
> >>>>
> >>>> On 26/01/2022 07:09, Florian Weimer wrote:
> >>>>> * Adhemerval Zanella via Libc-alpha:
> >>>>>
> >>>>>> diff --git a/scripts/tst-elf-edit.py b/scripts/tst-elf-edit.py
> >>>>>> new file mode 100644
> >>>>>> index 0000000000..1fb9b8e0fe
> >>>>>> --- /dev/null
> >>>>>> +++ b/scripts/tst-elf-edit.py
> >>>>>> @@ -0,0 +1,206 @@
> >>>>>
> >>>>>> +class Elf_Ehdr:
> >>>>>> +    def __init__(self, e_ident):
> >>>>>> +        endian, addr, off = elf_types_fmts(e_ident)
> >>>>>> +        self.fmt = '{0}HHI{1}{2}{2}IHHHHHH'.format(endian, addr, off)
> >>>>>> +        self.len = struct.calcsize(self.fmt)
> >>>>>> +
> >>>>>> +    def read(self, f):
> >>>>>> +        buf = f.read(self.len)
> >>>>>> +        if not buf:
> >>>>>> +            error('{}: header too small'.format(f.name))
> >>>>>
> >>>>> I think you need to check len(buf) < self.len.
> >>>>
> >>>> Ack.
> >>>>
> >>>>>
> >>>>>> +class Elf_Phdr:
> >>>>>> +    def __init__(self, e_ident):
> >>>>>> +        endian, addr, off = elf_types_fmts(e_ident)
> >>>>>> +        self.ei_class = e_ident[EI_CLASS]
> >>>>>> +        if self.ei_class == ELFCLASS32:
> >>>>>> +            self.fmt = '{0}I{2}{1}{1}IIII'.format(endian, addr, off)
> >>>>>> +        else:
> >>>>>> +            self.fmt = '{0}II{2}{1}{1}QQQ'.format(endian, addr, off)
> >>>>>> +        self.len = struct.calcsize(self.fmt)
> >>>>>> +
> >>>>>> +    def read(self, f):
> >>>>>> +        buf = f.read(self.len)
> >>>>>> +        if not buf:
> >>>>>> +            error('{}: program header too small'.format(f.name))
> >>>>>
> >>>>> Here as well.
> >>>>
> >>>> Ack.
> >>>>
> >>>>>
> >>>>> Rest looks okay.
> >>>>
> >>>> Thanks, I push it upstream with the above fixes installed.
> >>>
> >>> I got
> >>>
> >>> FAIL: elf/tst-p_align3
> >>>
> >>> [hjl@gnu-tgl-2 build-x86_64-linux]$ cat elf/tst-p_align3.out
> >>> /export/build/gnu/tools-build/glibc-cet-gitlab/build-x86_64-linux/elf/tst-p_align3:
> >>> error while loading shared libraries:
> >>> /export/build/gnu/tools-build/glibc-cet-gitlab/build-x86_64-linux/elf/tst-p_alignmod3.so:
> >>> cannot change memory protections
> >>> [hjl@gnu-tgl-2 build-x86_64-linux]$
> >>>
> >>> Only p_align should be changed to 0x100.  But I  saw
> >>
> >> I am not sure if this is related because tst-p_align3 and tst-alignmod3.so uses
> >> LDFLAGS instead:
> >>
> >> 1644 $(objpfx)tst-align3: $(objpfx)tst-alignmod3.so
> >> 1645 ifeq (yes,$(have-fpie))
> >> 1646 CFLAGS-tst-align3.c += $(PIE-ccflag)
> >> 1647 endif
> >> 1648 LDFLAGS-tst-align3 += -Wl,-z,max-page-size=0x200000
> >> 1649 LDFLAGS-tst-alignmod3.so += -Wl,-z,max-page-size=0x200000
> >> 1650 $(objpfx)tst-alignmod3.so: $(libsupport)
> >>
> >> And the patch only changed the way tst-p_align1 and tst-p_align2 modules were
> >> changed.
> >
> > It is tst-p_alignmod3.so, not tst-alignmod3.so.
> >             ^^
> My confusion here. But even though the script in not involved:
>
> 2622 LDFLAGS-tst-p_alignmod3.so += -Wl,-z,max-page-size=0x100,-z,common-page-size=0x100
> 2623
> 2624 $(objpfx)tst-p_align3: $(objpfx)tst-p_alignmod3.so
> 2625 $(objpfx)tst-p_align3.out: tst-p_align3.sh $(objpfx)tst-p_align3
> 2626         $(SHELL) $< $(common-objpfx) '$(test-program-prefix)'; \
> 2627         $(evaluate-test)
>
> That's why it is puzzling me that it start to fail now.

This test checks the invalid p_align handling.   You have to edit the
binary to change p_align to 0x100 which is invalid.

-- 
H.J.