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From:   "H.J. Lu" <hjl.tools@gmail.com>
Date:   Sun, 12 Dec 2021 05:52:14 -0800
Message-ID: <CAMe9rOqM+S_uBO-t5jJ1TLVD0R-LOJEiR6htb+k05c+ak7gF-g@mail.gmail.com>
Subject: Re: [PATCH] fs/binfmt_elf.c: disallow zero entry point address
To:     Alexey Dobriyan <adobriyan@gmail.com>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>
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On Sat, Dec 11, 2021 at 11:38 PM Alexey Dobriyan <adobriyan@gmail.com> wrote:
>
> On 12/11/21, H.J. Lu <hjl.tools@gmail.com> wrote:
> > According to gABI, the entry point address in the ELF header gives the
> > virtual address to which the system first transfers control, thus
> > starting the process.  If the file has no associated entry point, this
> > member holds zero.  Update the ELF loader to disallow an ELF binary
> > with zero entry point address.  This fixes:
> >
> > https://bugzilla.kernel.org/show_bug.cgi?id=215303
> >
> > Tested by booting Fedora 35 and running a shared library with zero entry
> > point address:
> >
> > $ readelf -h load.so | grep "Entry point address:"
> >   Entry point address:               0x0
> > $ ./load.so
> > bash: ./load.so: cannot execute binary file: Exec format error
>
> Why not let it segfault?
>
> > +     if (elf_ex->e_entry == 0)
> > +             goto out;

Why let it segfault?

-- 
H.J.