On Wed, Oct 21, 2020 at 02:12:41PM +0200, Thomas Zimmermann wrote:
> Trying to copy into the string fields with strncpy() gives a warning from
> gcc. Both fields are part of a packed HDMI header and do not require a
> terminating \0 character.
>
> ../drivers/video/hdmi.c: In function 'hdmi_spd_infoframe_init':
> ../drivers/video/hdmi.c:230:2: warning: 'strncpy' specified bound 8 equals destination size [-Wstringop-truncation]
> 230 | strncpy(frame->vendor, vendor, sizeof(frame->vendor));
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../drivers/video/hdmi.c:231:2: warning: 'strncpy' specified bound 16 equals destination size [-Wstringop-truncation]
> 231 | strncpy(frame->product, product, sizeof(frame->product));
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Just use memcpy() instead.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
I assume vendor is guaranteed to be 0-termindated.
Reviewed-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
> ---
> drivers/video/hdmi.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/video/hdmi.c b/drivers/video/hdmi.c
> index b7a1d6fae90d..1e4cb63d0d11 100644
> --- a/drivers/video/hdmi.c
> +++ b/drivers/video/hdmi.c
> @@ -221,14 +221,18 @@ EXPORT_SYMBOL(hdmi_avi_infoframe_pack);
> int hdmi_spd_infoframe_init(struct hdmi_spd_infoframe *frame,
> const char *vendor, const char *product)
> {
> + size_t len;
> +
> memset(frame, 0, sizeof(*frame));
>
> frame->type = HDMI_INFOFRAME_TYPE_SPD;
> frame->version = 1;
> frame->length = HDMI_SPD_INFOFRAME_SIZE;
>
> - strncpy(frame->vendor, vendor, sizeof(frame->vendor));
> - strncpy(frame->product, product, sizeof(frame->product));
> + len = strlen(vendor);
> + memcpy(frame->vendor, vendor, min(len, sizeof(frame->vendor)));
> + len = strlen(product);
> + memcpy(frame->product, product, min(len, sizeof(frame->product)));
>
> return 0;
> }
> --
> 2.28.0
>
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