On Thu, Aug 12, 2021 at 10:01 AM <trix@xxxxxxxxxx> wrote:
>
> From: Tom Rix <trix@xxxxxxxxxx>
>
> Static analysis reports this representative problem
>
> tda1997x.c:1939: warning: 7th function call argument is an uninitialized
> value
>
> The 7th argument is buffer[0], which is set in the earlier call to
> io_readn(). When io_readn() call to io_read() fails with the first
> read, buffer[0] is not set and 0 is returned and stored in len.
>
> The later call to hdmi_infoframe_unpack()'s size parameter is the
> static size of buffer, always 40, so a short read is not caught
> in hdmi_infoframe_unpacks()'s checking. The variable len should be
> used instead.
>
> Zero initialize buffer to 0 so it is in a known start state.
>
> Fixes: 9ac0038db9a7 ("media: i2c: Add TDA1997x HDMI receiver driver")
> Signed-off-by: Tom Rix <trix@xxxxxxxxxx>
> ---
> drivers/media/i2c/tda1997x.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/i2c/tda1997x.c b/drivers/media/i2c/tda1997x.c
> index 1e2a263be9335..0b995424cb346 100644
> --- a/drivers/media/i2c/tda1997x.c
> +++ b/drivers/media/i2c/tda1997x.c
> @@ -1248,13 +1248,13 @@ tda1997x_parse_infoframe(struct tda1997x_state *state, u16 addr)
> {
> struct v4l2_subdev *sd = &state->sd;
> union hdmi_infoframe frame;
> - u8 buffer[40];
> + u8 buffer[40] = { 0 };
> u8 reg;
> int len, err;
>
> /* read data */
> len = io_readn(sd, addr, sizeof(buffer), buffer);
> - err = hdmi_infoframe_unpack(&frame, buffer, sizeof(buffer));
> + err = hdmi_infoframe_unpack(&frame, buffer, len);
> if (err) {
> v4l_err(state->client,
> "failed parsing %d byte infoframe: 0x%04x/0x%02x\n",
> @@ -1928,13 +1928,13 @@ static int tda1997x_log_infoframe(struct v4l2_subdev *sd, int addr)
> {
> struct tda1997x_state *state = to_state(sd);
> union hdmi_infoframe frame;
> - u8 buffer[40];
> + u8 buffer[40] = { 0 };
> int len, err;
>
> /* read data */
> len = io_readn(sd, addr, sizeof(buffer), buffer);
> v4l2_dbg(1, debug, sd, "infoframe: addr=%d len=%d\n", addr, len);
> - err = hdmi_infoframe_unpack(&frame, buffer, sizeof(buffer));
> + err = hdmi_infoframe_unpack(&frame, buffer, len);
> if (err) {
> v4l_err(state->client,
> "failed parsing %d byte infoframe: 0x%04x/0x%02x\n",
> --
> 2.26.3
>
Reviewed-By: Tim Harvey <tharvey@xxxxxxxxxxxxx>
Tim
