media: TDA1997x: handle short reads of hdmi info frame.

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@redhat.com>
Reviewed-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

diff --git a/drivers/media/i2c/tda1997x.c b/drivers/media/i2c/tda1997x.c
index 1e2a263..0b99542 100644 (file)
--- 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",