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From:   "H.J. Lu" <hjl.tools@gmail.com>
Date:   Sun, 12 Dec 2021 11:05:52 -0800
Message-ID: <CAMe9rOqYxiMabie_2LN2mTTP7QPa0_mfKwDY10OSzKFj5GYT7A@mail.gmail.com>
Subject: Re: [PATCH] fs/binfmt_elf.c: disallow zero entry point address
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Alexey Dobriyan <adobriyan@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
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On Sun, Dec 12, 2021 at 10:29 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Sun, Dec 12, 2021 at 5:52 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > On Sat, Dec 11, 2021 at 11:38 PM Alexey Dobriyan <adobriyan@gmail.com> wrote:
> > >
> > > Why not let it segfault?
> >
> > Why let it segfault?
>
> That's not my main worry - what if somebody has a code section with a
> zero vaddr and intentionally put the entry at the beginning?
>
> Maybe it's not supposed to work by some paper standatd, but afaik
> currently it _would_ work.
>
> All these things are relative to the load address, so a zero e_entry
> doesn't mean NULL, and may be a perfectly valid address.
>
> No?

According to the ELF specification, zero entry point value means
there is no entry point.  Such ELF binary doesn't conform to the
ELF specification.

-- 
H.J.