| From bippy-1.1.0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@kernel.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2022-49884: KVM: Initialize gfn_to_pfn_cache locks in dedicated helper |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| KVM: Initialize gfn_to_pfn_cache locks in dedicated helper |
| |
| Move the gfn_to_pfn_cache lock initialization to another helper and |
| call the new helper during VM/vCPU creation. There are race |
| conditions possible due to kvm_gfn_to_pfn_cache_init()'s |
| ability to re-initialize the cache's locks. |
| |
| For example: a race between ioctl(KVM_XEN_HVM_EVTCHN_SEND) and |
| kvm_gfn_to_pfn_cache_init() leads to a corrupted shinfo gpc lock. |
| |
| (thread 1) | (thread 2) |
| | |
| kvm_xen_set_evtchn_fast | |
| read_lock_irqsave(&gpc->lock, ...) | |
| | kvm_gfn_to_pfn_cache_init |
| | rwlock_init(&gpc->lock) |
| read_unlock_irqrestore(&gpc->lock, ...) | |
| |
| Rename "cache_init" and "cache_destroy" to activate+deactivate to |
| avoid implying that the cache really is destroyed/freed. |
| |
| Note, there more races in the newly named kvm_gpc_activate() that will |
| be addressed separately. |
| |
| [sean: call out that this is a bug fix] |
| |
| The Linux kernel CVE team has assigned CVE-2022-49884 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.17 with commit 982ed0de4753ed6e71dbd40f82a5a066baf133ed and fixed in 6.0.8 with commit 61242001d6c9c253df7645dab090842d8da08764 |
| Issue introduced in 5.17 with commit 982ed0de4753ed6e71dbd40f82a5a066baf133ed and fixed in 6.1 with commit 52491a38b2c2411f3f0229dc6ad610349c704a41 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2022-49884 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| arch/x86/kvm/x86.c |
| arch/x86/kvm/xen.c |
| include/linux/kvm_host.h |
| virt/kvm/pfncache.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/61242001d6c9c253df7645dab090842d8da08764 |
| https://git.kernel.org/stable/c/52491a38b2c2411f3f0229dc6ad610349c704a41 |
