netdev - Re: [PATCH 05/10] ide: Remove uninitialized

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Message-ID: <CAKwvOdm5zDide5RuppY_jG=r46=UMdVJBrkBqD5x=dOMTG9cZg@mail.gmail.com>
Date:   Thu, 4 Jun 2020 12:29:17 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Joe Perches <joe@...ches.com>,
        Andy Whitcroft <apw@...onical.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        drbd-dev@...ts.linbit.com, linux-block@...r.kernel.org,
        b43-dev@...ts.infradead.org,
        Network Development <netdev@...r.kernel.org>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        linux-ide@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-spi@...r.kernel.org,
        Linux Memory Management List <linux-mm@...ck.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: Re: [PATCH 05/10] ide: Remove uninitialized_var() usage

On Wed, Jun 3, 2020 at 4:32 PM Kees Cook <keescook@...omium.org> wrote:
>
> Using uninitialized_var() is dangerous as it papers over real bugs[1]
> (or can in the future), and suppresses unrelated compiler warnings (e.g.
> "unused variable"). If the compiler thinks it is uninitialized, either
> simply initialize the variable or make compiler changes. As a precursor
> to removing[2] this[3] macro[4], just remove this variable since it was
> actually unused:
>
> drivers/ide/ide-taskfile.c:232:34: warning: unused variable 'flags' [-Wunused-variable]
>         unsigned long uninitialized_var(flags);
>                                         ^
>
> [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
> [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
> [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
> [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
>
> Signed-off-by: Kees Cook <keescook@...omium.org>

Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
Fixes ce1e518190ea ("ide: don't disable interrupts during kmap_atomic()")

> ---
>  drivers/ide/ide-taskfile.c | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/drivers/ide/ide-taskfile.c b/drivers/ide/ide-taskfile.c
> index aab6a10435b6..a26f85ab58a9 100644
> --- a/drivers/ide/ide-taskfile.c
> +++ b/drivers/ide/ide-taskfile.c
> @@ -229,7 +229,6 @@ void ide_pio_bytes(ide_drive_t *drive, struct ide_cmd *cmd,
>         ide_hwif_t *hwif = drive->hwif;
>         struct scatterlist *sg = hwif->sg_table;
>         struct scatterlist *cursg = cmd->cursg;
> -       unsigned long uninitialized_var(flags);
>         struct page *page;
>         unsigned int offset;
>         u8 *buf;
> --
> 2.25.1
>
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-- 
Thanks,
~Nick Desaulniers