linux-kernel - Re: [PATCH v2] platform: uv: fix missing checks for kcalloc

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Message-ID: <CAGXu5jJ_MdFE_aTc9rFY9SwympdXdJA9WhdaaPJo4UvP9OaqDg@mail.gmail.com>
Date:   Tue, 23 Apr 2019 13:02:43 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Kangjie Lu <kjlu@....edu>
Cc:     pakki001@....edu, Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, X86 ML <x86@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Andrew Banman <abanman@....com>,
        Varsha Rao <rvarsha016@...il.com>,
        Colin Ian King <colin.king@...onical.com>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Nicolai Stange <nstange@...e.de>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] platform: uv: fix missing checks for kcalloc

On Mon, Mar 25, 2019 at 1:29 PM Kangjie Lu <kjlu@....edu> wrote:
>
> In case kcalloc fails, the patch return an error to avoid
> potential NULL pointer dereference.
>
> Signed-off-by: Kangjie Lu <kjlu@....edu>

Reviewed-by: Kees Cook <keescook@...omium.org>

-Kees

>
> ---
> v2: reuse existing error path as suggested by
> Borislav Petkov <bp@...en8.de>
> ---
>  arch/x86/platform/uv/tlb_uv.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c
> index 2c53b0f19329..7b41b51b9a86 100644
> --- a/arch/x86/platform/uv/tlb_uv.c
> +++ b/arch/x86/platform/uv/tlb_uv.c
> @@ -2133,14 +2133,18 @@ static int __init summarize_uvhub_sockets(int nuvhubs,
>   */
>  static int __init init_per_cpu(int nuvhubs, int base_part_pnode)
>  {
> -       unsigned char *uvhub_mask;
>         struct uvhub_desc *uvhub_descs;
> +       unsigned char *uvhub_mask = NULL;
>
>         if (is_uv3_hub() || is_uv2_hub() || is_uv1_hub())
>                 timeout_us = calculate_destination_timeout();
>
>         uvhub_descs = kcalloc(nuvhubs, sizeof(struct uvhub_desc), GFP_KERNEL);
> +       if (!uvhub_descs)
> +               goto fail;
>         uvhub_mask = kzalloc((nuvhubs+7)/8, GFP_KERNEL);
> +       if (!uvhub_mask)
> +               goto fail;
>
>         if (get_cpu_topology(base_part_pnode, uvhub_descs, uvhub_mask))
>                 goto fail;
> --
> 2.17.1
>


-- 
Kees Cook