Bugzilla – Bug 1226535
VUL-0: CVE-2021-47575: kernel: xen/console: harden hvc_xen against event channel storms
Last modified: 2024-06-20 10:08:16 UTC
In the Linux kernel, the following vulnerability has been resolved: xen/console: harden hvc_xen against event channel storms The Xen console driver is still vulnerable for an attack via excessive number of events sent by the backend. Fix that by using a lateeoi event channel. For the normal domU initial console this requires the introduction of bind_evtchn_to_irq_lateeoi() as there is no xenbus device available at the time the event channel is bound to the irq. As the decision whether an interrupt was spurious or not requires to test for bytes having been read from the backend, move sending the event into the if statement, as sending an event without having found any bytes to be read is making no sense at all. This is part of XSA-391 --- V2: - slightly adapt spurious irq detection (Jan Beulich) V3: - fix spurious irq detection (Jan Beulich) References: http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-47575 https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2021/CVE-2021-47575.mbox https://git.kernel.org/stable/c/c7eaa5082bccfc00dfdb500ac6cc86d6f24ca027 https://git.kernel.org/stable/c/728389c21176b2095fa58e858d5ef1d2f2aac429 https://git.kernel.org/stable/c/68b78f976ca47d52c03c41eded207a312e46b934 https://git.kernel.org/stable/c/57e46acb3b48ea4e8efb1e1bea2e89e0c6cc43e2 https://git.kernel.org/stable/c/560e64413b4a6d9bd6630e350d5f2e6a05f6ffe3 https://git.kernel.org/stable/c/8fa3a370cc2af858a9ba662ca4f2bd0917550563 https://git.kernel.org/stable/c/153d1ea3272209fc970116f09051002d14422cde https://git.kernel.org/stable/c/fe415186b43df0db1f17fa3a46275fd92107fe71 https://www.cve.org/CVERecord?id=CVE-2021-47575