linux-kernel - Re: [PATCH] module: Harden STRICT_MODULE

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Message-ID: <20200410090407.GA8723@linux-8ccs.fritz.box>
Date:   Fri, 10 Apr 2020 11:04:08 +0200
From:   Jessica Yu <jeyu@...nel.org>
To:     Miroslav Benes <mbenes@...e.cz>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        keescook@...omium.org
Subject: Re: [PATCH] module: Harden STRICT_MODULE_RWX

+++ Miroslav Benes [09/04/20 18:55 +0200]:
>> I am still wondering if there are modules out there with sections flags
>> combination which would cause the same problem with layout_sections() and
>> move_module() logic I described earlier. But that it is a separate issue.
>
>And of course I misread the condition in layout_sections() and all should
>be fine. Oh well...

Me too :-( For some reason I misread it as an exact mask match, ugh.
In any case, it looks like we are fine since we'd catch all SHF_ALLOC
sections at the minimum and they would have sh_entsize set, and we
appropriately ignore non-SHF_ALLOC sections in move_module(), so
the hypothetical problem I described earlier was incorrect.