CVE-2021-47278

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

bus: mhi: pci_generic: Fix possible use-after-free in mhi_pci_remove()

This drivers remove path calls del_timer(). However, that function does not wait until the timer handler finishes. This means that the timer handler may still be running after the drivers remove function has finished, which would result in a use-after-free.

Fix by calling del_timer_sync(), which makes sure the timer handler has finished, and unable to re-schedule itself.

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 Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.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/0b67808ade8893a1b3608ddd74fac7854786c919
• https://git.kernel.org/stable/c/c597d5c59c7a6417dba06590f59b922e01188e8d
• https://git.kernel.org/stable/c/0b67808ade8893a1b3608ddd74fac7854786c919
• https://git.kernel.org/stable/c/c597d5c59c7a6417dba06590f59b922e01188e8d