media: dvb-frontends: dib7090p: fix null-ptr-deref in dib7090p_rw_on_apb()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: media: dvb-frontends: dib7090p: fix null-ptr-deref in dib7090p_rw_on_apb() 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()")

References

• https://git.kernel.org/stable/c/bc07cae4f36bb18d5b6a9ed835c1278ca44ec82e
• https://git.kernel.org/stable/c/ce8b7c711b9c4f040b5419729d0972db8e374324
• https://git.kernel.org/stable/c/529fd5593b721e6f4370c591f5086649ed149ff6
• https://git.kernel.org/stable/c/c33280d6bd668dbdc5a5f07887cc63a52ab4789c
• https://git.kernel.org/stable/c/09906650484a09b3a4d4b3d3065395856810becd
• https://git.kernel.org/stable/c/0bb32863426afe0badac25c28d59021f211d0f48
• https://git.kernel.org/stable/c/a0f744d6cdde81d7382e183f77a4080a39b206cd
• https://git.kernel.org/stable/c/19eb5d8e6aa1169d368a4d69aae5572950deb89d
• https://git.kernel.org/stable/c/ce5cac69b2edac3e3246fee03e8f4c2a1075238b