linux-kernel - Re: [PATCH] video/hdmi: prefer strlcpy to strncpy

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Date:   Tue, 29 May 2018 18:58:38 -0700
From:   Nick Desaulniers <nick.desaulniers@...il.com>
To:     b.zolnierkie@...sung.com
Cc:     Nick Desaulniers <nick.desaulniers@...il.com>,
        dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ebiggers@...gle.com
Subject: Re: [PATCH] video/hdmi: prefer strlcpy to strncpy

On Mon, May 28, 2018 at 11:59 PM, Nick Desaulniers
<nick.desaulniers@...il.com> wrote:
> Fixes a stringop-truncation warning from gcc-8.
>
> Signed-off-by: Nick Desaulniers <nick.desaulniers@...il.com>
> ---
>  drivers/video/hdmi.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/video/hdmi.c b/drivers/video/hdmi.c
> index 111a0ab..46c184c 100644
> --- a/drivers/video/hdmi.c
> +++ b/drivers/video/hdmi.c
> @@ -168,8 +168,8 @@ int hdmi_spd_infoframe_init(struct hdmi_spd_infoframe *frame,
>         frame->version = 1;
>         frame->length = HDMI_SPD_INFOFRAME_SIZE;
>
> -       strncpy(frame->vendor, vendor, sizeof(frame->vendor));
> -       strncpy(frame->product, product, sizeof(frame->product));
> +       strlcpy(frame->vendor, vendor, sizeof(frame->vendor));
> +       strlcpy(frame->product, product, sizeof(frame->product));
>
>         return 0;
>  }
> --
> 2.7.4
>

Eric points out this can leak kernel memory if size is less than length of src.