CVE-2021-47111: xen-netback: take a reference to the RX task thread
In the Linux kernel, the following vulnerability has been resolved:
xen-netback: take a reference to the RX task thread
Do this in order to prevent the task from being freed if the thread returns (which can be triggered by the frontend) before the call to kthreadstop done as part of the backend tear down. Not taking the reference will lead to a use-after-free in that scenario. Such reference was taken before but dropped as part of the rework done in 2ac061ce97f4.
Reintroduce the reference taking and add a comment this time explaining why it's needed.
This is XSA-374 / CVE-2021-28691.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2021-47111?
The severity of CVE-2021-47111 is classified as medium, indicating a moderate risk to affected systems.
How do I fix CVE-2021-47111?
To fix CVE-2021-47111, you should update the Linux kernel to the latest stable version that addresses the vulnerability.
Which versions of the Linux kernel are affected by CVE-2021-47111?
CVE-2021-47111 affects Linux kernel versions between 5.5 and 5.10.43, as well as 5.11 to 5.12.10, and specific release candidates for 5.13.
What kind of impact does CVE-2021-47111 have on systems?
CVE-2021-47111 can potentially allow a denial of service by causing a task thread to be improperly freed.
Is CVE-2021-47111 exploitable remotely?
CVE-2021-47111 is not considered remotely exploitable as it requires local access to trigger the vulnerability.