CVE-2021-28691

Guest triggered use-after-free in Linux xen-netback A malicious or buggy network PV frontend can force Linux netback to disable the interface and terminate the receive kernel thread associated with queue 0 in response to the frontend sending a malformed packet. Such kernel thread termination will lead to a use-after-free in Linux netback when the backend is destroyed, as the kernel thread associated with queue 0 will have already exited and thus the call to kthread_stop will be performed against a stale pointer.

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 Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.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://security.gentoo.org/glsa/202107-30
• https://security.netapp.com/advisory/ntap-20210805-0002/
• https://xenbits.xenproject.org/xsa/advisory-374.txt
• https://security.gentoo.org/glsa/202107-30
• https://security.netapp.com/advisory/ntap-20210805-0002/
• https://xenbits.xenproject.org/xsa/advisory-374.txt