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 <20190523161532.122421-1-natechancellor@gmail.com>
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From:   Stephen Hines <srhines@google.com>
Date:   Thu, 23 May 2019 09:46:38 -0700
Message-ID: <CAAzmS6_ENnGayTm6fbbbk8dojXrKUEB1P2_ZtP914_GCOaVOoQ@mail.gmail.com>
Subject: Re: [PATCH] misc: sgi-xp: Properly initialize buf in xpc_get_rsvd_page_pa
To:     Nathan Chancellor <natechancellor@gmail.com>
Cc:     Cliff Whickman <cpw@sgi.com>, Robin Holt <robinmholt@gmail.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
        Nick Desaulniers <ndesaulniers@google.com>
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Looks good to me. :) Since I don't contribute to the Linux kernel
directly, I appreciate you picking this up.

Thanks,
Steve

On Thu, May 23, 2019 at 9:20 AM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> Clang warns:
>
> drivers/misc/sgi-xp/xpc_partition.c:73:14: warning: variable 'buf' is
> uninitialized when used within its own initialization [-Wuninitialized]
>         void *buf = buf;
>               ~~~   ^~~
> 1 warning generated.
>
> Initialize it to NULL, which is more deterministic.
>
> Fixes: 279290294662 ("[IA64-SGI] cleanup the way XPC locates the reserved page")
> Link: https://github.com/ClangBuiltLinux/linux/issues/466
> Suggested-by: Stephen Hines <srhines@google.com>
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
>
> Thanks Steve for the suggestion, don't know why that never crossed my
> mind...
>
> I tried to follow buf all the way down in get_partition_rsvd_page to see
> if there would be any dereferences and I didn't see any but I could
> have easily missed something.
>
>  drivers/misc/sgi-xp/xpc_partition.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/misc/sgi-xp/xpc_partition.c b/drivers/misc/sgi-xp/xpc_partition.c
> index 3eba1c420cc0..782ce95d3f17 100644
> --- a/drivers/misc/sgi-xp/xpc_partition.c
> +++ b/drivers/misc/sgi-xp/xpc_partition.c
> @@ -70,7 +70,7 @@ xpc_get_rsvd_page_pa(int nasid)
>         unsigned long rp_pa = nasid;    /* seed with nasid */
>         size_t len = 0;
>         size_t buf_len = 0;
> -       void *buf = buf;
> +       void *buf = NULL;
>         void *buf_base = NULL;
>         enum xp_retval (*get_partition_rsvd_page_pa)
>                 (void *, u64 *, unsigned long *, size_t *) =
> --
> 2.22.0.rc1
>