CVE-2022-48854

In the Linux kernel, the following vulnerability has been resolved:

net: arc_emac: Fix use after free in arc_mdio_probe()

If bus->state is equal to MDIOBUS_ALLOCATED, mdiobus_free(bus) will free the bus. But bus->name is still used in the next line, which will lead to a use after free.

We can fix it by putting the name in a local variable and make the bus->name point to the rodata section name,then use the name in the error message without referring to bus to avoid the uaf.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/84c831803785c2c3bec5c28c0e8a0b72f6b41d4d
• https://git.kernel.org/stable/c/bc0e610a6eb0d46e4123fafdbe5e6141d9fff3be
• https://git.kernel.org/stable/c/84c831803785c2c3bec5c28c0e8a0b72f6b41d4d
• https://git.kernel.org/stable/c/bc0e610a6eb0d46e4123fafdbe5e6141d9fff3be