CVE-2021-47088

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

mm/damon/dbgfs: protect targets destructions with kdamond_lock

DAMON debugfs interface iterates current monitoring targets in dbgfs_target_ids_read() while holding the corresponding kdamond_lock. However, it also destructs the monitoring targets in dbgfs_before_terminate() without holding the lock. This can result in a use_after_free bug. This commit avoids the race by protecting the destruction with the corresponding kdamond_lock.

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 Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.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/330c6117a82c16a9a365a51cec5c9ab30b13245c
• https://git.kernel.org/stable/c/34796417964b8d0aef45a99cf6c2d20cebe33733
• https://git.kernel.org/stable/c/330c6117a82c16a9a365a51cec5c9ab30b13245c
• https://git.kernel.org/stable/c/34796417964b8d0aef45a99cf6c2d20cebe33733