| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2022-48943: KVM: x86/mmu: make apf token non-zero to fix bug |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| KVM: x86/mmu: make apf token non-zero to fix bug |
| |
| In current async pagefault logic, when a page is ready, KVM relies on |
| kvm_arch_can_dequeue_async_page_present() to determine whether to deliver |
| a READY event to the Guest. This function test token value of struct |
| kvm_vcpu_pv_apf_data, which must be reset to zero by Guest kernel when a |
| READY event is finished by Guest. If value is zero meaning that a READY |
| event is done, so the KVM can deliver another. |
| But the kvm_arch_setup_async_pf() may produce a valid token with zero |
| value, which is confused with previous mention and may lead the loss of |
| this READY event. |
| |
| This bug may cause task blocked forever in Guest: |
| INFO: task stress:7532 blocked for more than 1254 seconds. |
| Not tainted 5.10.0 #16 |
| "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. |
| task:stress state:D stack: 0 pid: 7532 ppid: 1409 |
| flags:0x00000080 |
| Call Trace: |
| __schedule+0x1e7/0x650 |
| schedule+0x46/0xb0 |
| kvm_async_pf_task_wait_schedule+0xad/0xe0 |
| ? exit_to_user_mode_prepare+0x60/0x70 |
| __kvm_handle_async_pf+0x4f/0xb0 |
| ? asm_exc_page_fault+0x8/0x30 |
| exc_page_fault+0x6f/0x110 |
| ? asm_exc_page_fault+0x8/0x30 |
| asm_exc_page_fault+0x1e/0x30 |
| RIP: 0033:0x402d00 |
| RSP: 002b:00007ffd31912500 EFLAGS: 00010206 |
| RAX: 0000000000071000 RBX: ffffffffffffffff RCX: 00000000021a32b0 |
| RDX: 000000000007d011 RSI: 000000000007d000 RDI: 00000000021262b0 |
| RBP: 00000000021262b0 R08: 0000000000000003 R09: 0000000000000086 |
| R10: 00000000000000eb R11: 00007fefbdf2baa0 R12: 0000000000000000 |
| R13: 0000000000000002 R14: 000000000007d000 R15: 0000000000001000 |
| |
| The Linux kernel CVE team has assigned CVE-2022-48943 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 5.10.103 with commit 72fdfc75d4217b32363cc80def3de2cb3fef3f02 |
| Fixed in 5.15.26 with commit 4c3644b6c96c5daa5149e5abddc07234eea47c7c |
| Fixed in 5.16.12 with commit 62040f5cd7d937de547836e747b6aa8212fec573 |
| Fixed in 5.17 with commit 6f3c1fc53d86d580d8d6d749c4af23705e4f6f79 |
| |
| 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-2022-48943 |
| 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/mmu/mmu.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/72fdfc75d4217b32363cc80def3de2cb3fef3f02 |
| https://git.kernel.org/stable/c/4c3644b6c96c5daa5149e5abddc07234eea47c7c |
| https://git.kernel.org/stable/c/62040f5cd7d937de547836e747b6aa8212fec573 |
| https://git.kernel.org/stable/c/6f3c1fc53d86d580d8d6d749c4af23705e4f6f79 |
