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.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-28691
• https://security.gentoo.org/glsa/202107-30
• https://security.netapp.com/advisory/ntap-20210805-0002/
• https://xenbits.xenproject.org/xsa/advisory-374.txt