[media.git/next] media: dvb-frontends: dib7090p: fix null-ptr-deref in dib7090p_rw_on_apb()

[media-ci]

On Sun Jun 15 21:32:31 2025 -0400, Alex Guo wrote:
> In dib7090p_rw_on_apb, msg is controlled by user. When msg[0].buf is null and
> msg[0].len is zero, former checks on msg[0].buf would be passed. If accessing
> msg[0].buf[2] without sanity check, null pointer deref would happen. We add
> check on msg[0].len to prevent crash. Similar issue occurs when access
> msg[1].buf[0] and msg[1].buf[1].
> 
> Similar commit: commit 0ed554fd769a ("media: dvb-usb: az6027: fix 
> null-ptr-deref in az6027_i2c_xfer()")
> 
> Signed-off-by: Alex Guo <alexguo1...@gmail.com>
> Link: https://lore.kernel.org/r/20250616013231.730221-1-alexguo1...@gmail.com
> Signed-off-by: Mauro Carvalho Chehab <mchehab+hua...@kernel.org>

Patch committed.

Thanks,
Mauro Carvalho Chehab

 drivers/media/dvb-frontends/dib7000p.c | 4 ++++
 1 file changed, 4 insertions(+)

---

diff --git a/drivers/media/dvb-frontends/dib7000p.c 
b/drivers/media/dvb-frontends/dib7000p.c
index 2c2354dd547d..7d3a994b7cc4 100644
--- a/drivers/media/dvb-frontends/dib7000p.c
+++ b/drivers/media/dvb-frontends/dib7000p.c
@@ -2260,8 +2260,12 @@ static int dib7090p_rw_on_apb(struct i2c_adapter 
*i2c_adap,
        u16 word;
 
        if (num == 1) {         /* write */
+               if (msg[0].len < 3)
+                       return -EOPNOTSUPP;
                dib7000p_write_word(state, apb_address, ((msg[0].buf[1] << 8) | 
(msg[0].buf[2])));
        } else {
+               if (msg[1].len < 2)
+                       return -EOPNOTSUPP;
                word = dib7000p_read_word(state, apb_address);
                msg[1].buf[0] = (word >> 8) & 0xff;
                msg[1].buf[1] = (word) & 0xff;