linux-kernel - Re: [PATCH 3.12 69/72] Revert "fix minor infoleak in get_user

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Message-ID: <CA+55aFwXuut8k29cYqnCGjgk9Ymq--Zjfziz+sM__FVLoTJu+A@mail.gmail.com>
Date:   Mon, 7 Nov 2016 08:45:59 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Jiri Slaby <jslaby@...e.cz>, Greg KH <greg@...ah.com>
Cc:     stable <stable@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH 3.12 69/72] Revert "fix minor infoleak in get_user_ex()"

So a patch something like this might be a safe way to fix the
potential infoleak in older kernels.

THIS IS UNTESTED. It's a very obvious patch, though, so if it compiles
it probably works. It just initializes the output variable with 0 in
the inline asm description, instead of doing it in the exception
handler.

It will generate slightly worse code (a few unnecessary ALU
operations), but it doesn't have any interactions with the exception
handler implementation.

                  Linus

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