media: dvb-frontends: w7090p: fix null-ptr-deref in w7090p_tuner_write_serpar and w7090p_tuner_read_serpar

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: media: dvb-frontends: w7090p: fix null-ptr-deref in w7090p_tuner_write_serpar and w7090p_tuner_read_serpar In w7090p_tuner_write_serpar, 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 commit: commit 0ed554fd769a ("media: dvb-usb: az6027: fix null-ptr-deref in az6027_i2c_xfer()")

References

• https://git.kernel.org/stable/c/7a41ecfc3415ebe3b4c44f96b3337691dcf431a3
• https://git.kernel.org/stable/c/b3d77a3fc71c084575d3df4ec6544b3fb6ce587d
• https://git.kernel.org/stable/c/17b30e5ded062bd74f8ca6f317e1d415a8680665
• https://git.kernel.org/stable/c/454a443eaa792c8865c861a282fe6d4f596abc3a
• https://git.kernel.org/stable/c/6bbaec6a036940e22318f0454b50b8000845ab59
• https://git.kernel.org/stable/c/f98132a59ccc59a8b97987363bc99c8968934756
• https://git.kernel.org/stable/c/99690a494d91a0dc86cebd628da4c62c40552bcb
• https://git.kernel.org/stable/c/39b06b93f24dff923c4183d564ed28c039150554
• https://git.kernel.org/stable/c/ed0234c8458b3149f15e496b48a1c9874dd24a1b