net: ethernet: stmmac: fix altr_tse_pcs function when using a fixed-link

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: net: ethernet: stmmac: fix altr_tse_pcs function when using a fixed-link When using a fixed-link, the altr_tse_pcs driver crashes due to null-pointer dereference as no phy_device is provided to tse_pcs_fix_mac_speed function. Fix this by adding a check for phy_dev before calling the tse_pcs_fix_mac_speed() function. Also clean up the tse_pcs_fix_mac_speed function a bit. There is no need to check for splitter_base and sgmii_adapter_base because the driver will fail if these 2 variables are not derived from the device tree.

References

• https://git.kernel.org/stable/c/7e59fdf9547c4f948d1d917ec7ffa5fb5ac53bdb
• https://git.kernel.org/stable/c/08d5e3e954537931c8da7428034808d202e98299
• https://git.kernel.org/stable/c/62a48383ebe2e159fd68425dd3e16d4c6bd6599a
• https://git.kernel.org/stable/c/6c020f05253df04c3480b586fe188a3582740049
• https://git.kernel.org/stable/c/a6aaa00324240967272b451bfa772547bd576ee6