linux-kernel - Re: [PATCH v3] exec: load_script: Do not exec truncated interpreter path

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Message-ID: <CAHk-=whiDx=2=U=0-uSaVVb4kC_Wz7y=cbFi+Ub+1hQEb7WyuQ@mail.gmail.com>
Date:   Fri, 15 Feb 2019 08:05:56 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Oleg Nesterov <oleg@...hat.com>,
        Samuel Dionne-Riel <samuel@...nne-riel.com>,
        Richard Weinberger <richard.weinberger@...il.com>,
        Graham Christensen <graham@...hamc.com>,
        Michal Hocko <mhocko@...e.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] exec: load_script: Do not exec truncated interpreter path

On Fri, Feb 15, 2019 at 7:54 AM Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> What's wrong with this simple and fairly self-describing patch?

Simple but with two bugs.

First off, the trivial one: I transposed the arguments to memchr(). It
would need to be

        cp = memchr(bprm->buf, '\n', BINPRM_BUF_SIZE);

because I never use memchr().

And even that doesn't really fix it, because what it really wants is
"strnchr()" (to stop at a NUL too). Which doesn't exist.

So skip that patch, it's wrong.

                Linus