Describe CVE-2021-47273.
What is CVE-2021-47273?
In the Linux kernel, the following vulnerability has been resolved:

usb: dwc3-meson-g12a: fix usb2 PHY glue init when phy0 is disabled

When only PHY1 is used (for example on Odroid-HC4), the regmap init code
uses the usb2 ports when doesn't initialize the PHY1 regmap entry.

This fixes:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020
...
pc : regmap_update_bits_base+0x40/0xa0
lr : dwc3_meson_g12a_usb2_init_phy+0x4c/0xf8
...
Call trace:
regmap_update_bits_base+0x40/0xa0
dwc3_meson_g12a_usb2_init_phy+0x4c/0xf8
dwc3_meson_g12a_usb2_init+0x7c/0xc8
dwc3_meson_g12a_usb_init+0x28/0x48
dwc3_meson_g12a_probe+0x298/0x540
platform_probe+0x70/0xe0
really_probe+0xf0/0x4d8
driver_probe_device+0xfc/0x168
....