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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Mon, 13 Sep 2021 13:10:21 -0700
Message-ID: <CAHk-=whwREzjT7=OSi5=qqOkQsvMkCOYVhyKQ5t8Rdq4bBEzuw@mail.gmail.com>
Subject: Re: [PATCH 5.14 018/334] nbd: add the check to prevent overflow in __nbd_ioctl()
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Sedat Dilek <sedat.dilek@gmail.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Naresh Kamboju <naresh.kamboju@linaro.org>,
        Nathan Chancellor <natechancellor@gmail.com>,
        Baokun Li <libaokun1@huawei.com>,
        open list <linux-kernel@vger.kernel.org>,
        linux-stable <stable@vger.kernel.org>,
        Hulk Robot <hulkci@huawei.com>,
        Josef Bacik <josef@toxicpanda.com>,
        Jens Axboe <axboe@kernel.dk>, Sasha Levin <sashal@kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        lkft-triage@lists.linaro.org, llvm@lists.linux.dev,
        Kees Cook <keescook@chromium.org>
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On Mon, Sep 13, 2021 at 1:02 PM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> Ha! I pulled+rebased and this code disappeared...I thought I had
> rebased on the wrong branch or committed work to master accidentally.
> Patch to stable-only inbound.

Side note: for stable, can you look into using _Generic() instead of
__builtin_choose_expression() with typeof, or some
__builtin_types_compatible_p() magic?

Yes, yes, we use __builtin_choose_expression() elsewhere, but we've
started using _Generic(), and it's really the more natural model - in
addition to being the standard C one.

Of course, there may be some reason why _Generic() doesn't work, but
it _is_ the natural fit for any "for type X, do Y" kind of thing.

No?

          Linus