CVE-2024-26976

一、漏洞信息
 漏洞编号：[CVE-2024-26976](https://nvd.nist.gov/vuln/detail/CVE-2024-26976)
 漏洞归属组件：[kernel](https://gitee.com/src-openeuler/kernel)
 漏洞归属的版本：4.19.140,4.19.194,4.19.90,5.10.0,6.1.0,6.1.14,6.1.19,6.1.5,6.1.6,6.1.8,6.4.0,6.6.0
 CVSS V2.0分值：
  BaseScore：0.0 Low
  Vector：CVSS：2.0/
 漏洞简述：
  In the Linux kernel, the following vulnerability has been resolved:KVM: Always flush async #PF workqueue when vCPU is being destroyedAlways flush the per-vCPU async #PF workqueue when a vCPU is clearing itscompletion queue, e.g. when a VM and all its vCPUs is being destroyed.KVM must ensure that none of its workqueue callbacks is running when thelast reference to the KVM _module_ is put.  Gifting a reference to theassociated VM prevents the workqueue callback from dereferencing freedvCPU/VM memory, but does not prevent the KVM module from being unloadedbefore the callback completes.Drop the misguided VM refcount gifting, as calling kvm_put_kvm() fromasync_pf_execute() if kvm_put_kvm() flushes the async #PF workqueue willresult in deadlock.  async_pf_execute() can t return until kvm_put_kvm()finishes, and kvm_put_kvm() can t return until async_pf_execute() finishes: WARNING: CPU: 8 PID: 251 at virt/kvm/kvm_main.c:1435 kvm_put_kvm+0x2d/0x320 [kvm] Modules linked in: vhost_net vhost vhost_iotlb tap kvm_intel kvm irqbypass CPU: 8 PID: 251 Comm: kworker/8:1 Tainted: G        W          6.6.0-rc1-e7af8d17224a-x86/gmem-vm #119 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 Workqueue: events async_pf_execute [kvm] RIP: 0010:kvm_put_kvm+0x2d/0x320 [kvm] Call Trace:  <TASK>  async_pf_execute+0x198/0x260 [kvm]  process_one_work+0x145/0x2d0  worker_thread+0x27e/0x3a0  kthread+0xba/0xe0  ret_from_fork+0x2d/0x50  ret_from_fork_asm+0x11/0x20  </TASK> ---[ end trace 0000000000000000 ]--- INFO: task kworker/8:1:251 blocked for more than 120 seconds.       Tainted: G        W          6.6.0-rc1-e7af8d17224a-x86/gmem-vm #119  echo 0 > /proc/sys/kernel/hung_task_timeout_secs  disables this message. task:kworker/8:1     state:D stack:0     pid:251   ppid:2      flags:0x00004000 Workqueue: events async_pf_execute [kvm] Call Trace:  <TASK>  __schedule+0x33f/0xa40  schedule+0x53/0xc0  schedule_timeout+0x12a/0x140  __wait_for_common+0x8d/0x1d0  __flush_work.isra.0+0x19f/0x2c0  kvm_clear_async_pf_completion_queue+0x129/0x190 [kvm]  kvm_arch_destroy_vm+0x78/0x1b0 [kvm]  kvm_put_kvm+0x1c1/0x320 [kvm]  async_pf_execute+0x198/0x260 [kvm]  process_one_work+0x145/0x2d0  worker_thread+0x27e/0x3a0  kthread+0xba/0xe0  ret_from_fork+0x2d/0x50  ret_from_fork_asm+0x11/0x20  </TASK>If kvm_clear_async_pf_completion_queue() actually flushes the workqueue,then there s no need to gift async_pf_execute() a reference because allinvocations of async_pf_execute() will be forced to complete before thevCPU and its VM are destroyed/freed.  And that in turn fixes the moduleunloading bug as __fput() won t do module_put() on the last vCPU referenceuntil the vCPU has been freed, e.g. if closing the vCPU file also puts thelast reference to the KVM module.Note that kvm_check_async_pf_completion() may also take the work item offthe completion queue and so also needs to flush the work queue, as thework will not be seen by kvm_clear_async_pf_completion_queue().  Waitingon the workqueue could theoretically delay a vCPU due to waiting for thework to complete, but that s a very, very small chance, and likely a verysmall delay.  kvm_arch_async_page_present_queued() unconditionally makes anew request, i.e. will effectively delay entering the guest, so theremaining work is really just:        trace_kvm_async_pf_completed(addr, cr2_or_gpa);        __kvm_vcpu_wake_up(vcpu);        mmput(mm);and mmput() can t drop the last reference to the page tables if the vCPU isstill alive, i.e. the vCPU won t get stuck tearing down page tables.Add a helper to do the flushing, specifically to deal with  wakeup all work items, as they aren t actually work items, i.e. are never placed in aworkqueue.  Trying to flush a bogus workqueue entry rightly makes__flush_work() complain (kudos to whoever added that sanity check).Note, commit 5f6de5cbebee ( KVM: Prevent module exit until al---truncated---
 漏洞公开时间：2024-05-01 14:15:14
 漏洞创建时间：2024-05-01 14:37:15
 漏洞详情参考链接：
  https://nvd.nist.gov/vuln/detail/CVE-2024-26976
<details>
<summary>更多参考(点击展开)</summary>

| 参考来源 | 参考链接 | 来源链接 |
| ------- | -------- | -------- |
| 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | https://git.kernel.org/stable/c/3d75b8aa5c29058a512db29da7cbee8052724157 |  |
| 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | https://git.kernel.org/stable/c/4f3a3bce428fb439c66a578adc447afce7b4a750 |  |
| 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | https://git.kernel.org/stable/c/82e25cc1c2e93c3023da98be282322fc08b61ffb |  |
| 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | https://git.kernel.org/stable/c/83d3c5e309611ef593e2fcb78444fc8ceedf9bac |  |
| 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | https://git.kernel.org/stable/c/a75afe480d4349c524d9c659b1a5a544dbc39a98 |  |
| 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | https://git.kernel.org/stable/c/ab2c2f5d9576112ad22cfd3798071cb74693b1f5 |  |
| 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | https://git.kernel.org/stable/c/b54478d20375874aeee257744dedfd3e413432ff |  |
| 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | https://git.kernel.org/stable/c/caa9af2e27c275e089d702cfbaaece3b42bca31b |  |
| 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | https://git.kernel.org/stable/c/f8730d6335e5f43d09151fca1f0f41922209a264 |  |
| suse_bugzilla | http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2024-26976 | https://bugzilla.suse.com/show_bug.cgi?id=1223635 |
| suse_bugzilla | https://www.cve.org/CVERecord?id=CVE-2024-26976 | https://bugzilla.suse.com/show_bug.cgi?id=1223635 |
| suse_bugzilla | https://git.kernel.org/stable/c/3d75b8aa5c29058a512db29da7cbee8052724157 | https://bugzilla.suse.com/show_bug.cgi?id=1223635 |
| suse_bugzilla | https://git.kernel.org/stable/c/4f3a3bce428fb439c66a578adc447afce7b4a750 | https://bugzilla.suse.com/show_bug.cgi?id=1223635 |
| suse_bugzilla | https://git.kernel.org/stable/c/82e25cc1c2e93c3023da98be282322fc08b61ffb | https://bugzilla.suse.com/show_bug.cgi?id=1223635 |
| suse_bugzilla | https://git.kernel.org/stable/c/83d3c5e309611ef593e2fcb78444fc8ceedf9bac | https://bugzilla.suse.com/show_bug.cgi?id=1223635 |
| suse_bugzilla | https://git.kernel.org/stable/c/a75afe480d4349c524d9c659b1a5a544dbc39a98 | https://bugzilla.suse.com/show_bug.cgi?id=1223635 |
| suse_bugzilla | https://git.kernel.org/stable/c/ab2c2f5d9576112ad22cfd3798071cb74693b1f5 | https://bugzilla.suse.com/show_bug.cgi?id=1223635 |
| suse_bugzilla | https://git.kernel.org/stable/c/b54478d20375874aeee257744dedfd3e413432ff | https://bugzilla.suse.com/show_bug.cgi?id=1223635 |
| suse_bugzilla | https://git.kernel.org/stable/c/caa9af2e27c275e089d702cfbaaece3b42bca31b | https://bugzilla.suse.com/show_bug.cgi?id=1223635 |
| suse_bugzilla | https://git.kernel.org/stable/c/f8730d6335e5f43d09151fca1f0f41922209a264 | https://bugzilla.suse.com/show_bug.cgi?id=1223635 |
| suse_bugzilla | https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2024/CVE-2024-26976.mbox | https://bugzilla.suse.com/show_bug.cgi?id=1223635 |
| suse_bugzilla | https://bugzilla.redhat.com/show_bug.cgi?id=2278350 | https://bugzilla.suse.com/show_bug.cgi?id=1223635 |
| ubuntu | https://www.cve.org/CVERecord?id=CVE-2024-26976 | https://ubuntu.com/security/CVE-2024-26976 |
| ubuntu | https://git.kernel.org/linus/3d75b8aa5c29058a512db29da7cbee8052724157 (6.9-rc1) | https://ubuntu.com/security/CVE-2024-26976 |
| ubuntu | https://git.kernel.org/stable/c/ab2c2f5d9576112ad22cfd3798071cb74693b1f5 | https://ubuntu.com/security/CVE-2024-26976 |
| ubuntu | https://git.kernel.org/stable/c/82e25cc1c2e93c3023da98be282322fc08b61ffb | https://ubuntu.com/security/CVE-2024-26976 |
| ubuntu | https://git.kernel.org/stable/c/f8730d6335e5f43d09151fca1f0f41922209a264 | https://ubuntu.com/security/CVE-2024-26976 |
| ubuntu | https://git.kernel.org/stable/c/83d3c5e309611ef593e2fcb78444fc8ceedf9bac | https://ubuntu.com/security/CVE-2024-26976 |
| ubuntu | https://git.kernel.org/stable/c/b54478d20375874aeee257744dedfd3e413432ff | https://ubuntu.com/security/CVE-2024-26976 |
| ubuntu | https://git.kernel.org/stable/c/a75afe480d4349c524d9c659b1a5a544dbc39a98 | https://ubuntu.com/security/CVE-2024-26976 |
| ubuntu | https://git.kernel.org/stable/c/4f3a3bce428fb439c66a578adc447afce7b4a750 | https://ubuntu.com/security/CVE-2024-26976 |
| ubuntu | https://git.kernel.org/stable/c/caa9af2e27c275e089d702cfbaaece3b42bca31b | https://ubuntu.com/security/CVE-2024-26976 |
| ubuntu | https://git.kernel.org/stable/c/3d75b8aa5c29058a512db29da7cbee8052724157 | https://ubuntu.com/security/CVE-2024-26976 |
| ubuntu | https://nvd.nist.gov/vuln/detail/CVE-2024-26976 | https://ubuntu.com/security/CVE-2024-26976 |
| ubuntu | https://launchpad.net/bugs/cve/CVE-2024-26976 | https://ubuntu.com/security/CVE-2024-26976 |
| ubuntu | https://security-tracker.debian.org/tracker/CVE-2024-26976 | https://ubuntu.com/security/CVE-2024-26976 |
| debian |  | https://security-tracker.debian.org/tracker/CVE-2024-26976 |

</details>

漏洞分析指导链接：
  https://gitee.com/openeuler/cve-manager/blob/master/cve-vulner-manager/doc/md/manual.md
 漏洞数据来源:
  openBrain开源漏洞感知系统
 漏洞补丁信息：
  <details>
<summary>详情(点击展开)</summary>

| 影响的包 | 修复版本 | 修复补丁 | 问题引入补丁 | 来源  |
| ------- | -------- | ------- | -------- | --------- |
| linux |  | https://git.kernel.org/linus/3d75b8aa5c29058a512db29da7cbee8052724157 | https://git.kernel.org/linus/af585b921e5d1e919947c4b1164b59507fe7cd7b | ubuntu |

</details>

二、漏洞分析结构反馈
 影响性分析说明：
    In the Linux kernel, the following vulnerability has been resolved:KVM: Always flush async #PF workqueue when vCPU is being destroyedAlways flush the per-vCPU async #PF workqueue when a vCPU is clearing itscompletion queue, e.g. when a VM and all its vCPUs is being destroyed.KVM must ensure that none of its workqueue callbacks is running when thelast reference to the KVM _module_ is put.  Gifting a reference to theassociated VM prevents the workqueue callback from dereferencing freedvCPU/VM memory, but does not prevent the KVM module from being unloadedbefore the callback completes.Drop the misguided VM refcount gifting, as calling kvm_put_kvm() fromasync_pf_execute() if kvm_put_kvm() flushes the async #PF workqueue willresult in deadlock.  async_pf_execute() can t return until kvm_put_kvm()finishes, and kvm_put_kvm() can t return until async_pf_execute() finishes: WARNING: CPU: 8 PID: 251 at virt/kvm/kvm_main.c:1435 kvm_put_kvm+0x2d/0x320 [kvm] Modules linked in: vhost_net vhost vhost_iotlb tap kvm_intel kvm irqbypass CPU: 8 PID: 251 Comm: kworker/8:1 Tainted: G        W          6.6.0-rc1-e7af8d17224a-x86/gmem-vm #119 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 Workqueue: events async_pf_execute [kvm] RIP: 0010:kvm_put_kvm+0x2d/0x320 [kvm] Call Trace:  <TASK>  async_pf_execute+0x198/0x260 [kvm]  process_one_work+0x145/0x2d0  worker_thread+0x27e/0x3a0  kthread+0xba/0xe0  ret_from_fork+0x2d/0x50  ret_from_fork_asm+0x11/0x20  </TASK> ---[ end trace 0000000000000000 ]--- INFO: task kworker/8:1:251 blocked for more than 120 seconds.       Tainted: G        W          6.6.0-rc1-e7af8d17224a-x86/gmem-vm #119  echo 0 > /proc/sys/kernel/hung_task_timeout_secs  disables this message. task:kworker/8:1     state:D stack:0     pid:251   ppid:2      flags:0x00004000 Workqueue: events async_pf_execute [kvm] Call Trace:  <TASK>  __schedule+0x33f/0xa40  schedule+0x53/0xc0  schedule_timeout+0x12a/0x140  __wait_for_common+0x8d/0x1d0  __flush_work.isra.0+0x19f/0x2c0  kvm_clear_async_pf_completion_queue+0x129/0x190 [kvm]  kvm_arch_destroy_vm+0x78/0x1b0 [kvm]  kvm_put_kvm+0x1c1/0x320 [kvm]  async_pf_execute+0x198/0x260 [kvm]  process_one_work+0x145/0x2d0  worker_thread+0x27e/0x3a0  kthread+0xba/0xe0  ret_from_fork+0x2d/0x50  ret_from_fork_asm+0x11/0x20  </TASK>If kvm_clear_async_pf_completion_queue() actually flushes the workqueue,then there s no need to gift async_pf_execute() a reference because allinvocations of async_pf_execute() will be forced to complete before thevCPU and its VM are destroyed/freed.  And that in turn fixes the moduleunloading bug as __fput() won t do module_put() on the last vCPU referenceuntil the vCPU has been freed, e.g. if closing the vCPU file also puts thelast reference to the KVM module.Note that kvm_check_async_pf_completion() may also take the work item offthe completion queue and so also needs to flush the work queue, as thework will not be seen by kvm_clear_async_pf_completion_queue().  Waitingon the workqueue could theoretically delay a vCPU due to waiting for thework to complete, but that s a very, very small chance, and likely a verysmall delay.  kvm_arch_async_page_present_queued() unconditionally makes anew request, i.e. will effectively delay entering the guest, so theremaining work is really just:        trace_kvm_async_pf_completed(addr, cr2_or_gpa);        __kvm_vcpu_wake_up(vcpu);        mmput(mm);and mmput() can t drop the last reference to the page tables if the vCPU isstill alive, i.e. the vCPU won t get stuck tearing down page tables.Add a helper to do the flushing, specifically to deal with  wakeup all work items, as they aren t actually work items, i.e. are never placed in aworkqueue.  Trying to flush a bogus workqueue entry rightly makes__flush_work() complain (kudos to whoever added that sanity check).Note, commit 5f6de5cbebee ( KVM: Prevent module exit until al---truncated--- 
 openEuler评分：
  5.5
 Vector：CVSS：2.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
 受影响版本排查(受影响/不受影响)：
  1.openEuler-20.03-LTS-SP1(4.19.90):受影响
2.openEuler-20.03-LTS-SP4:受影响
3.openEuler-22.03-LTS(5.10.0):受影响
4.openEuler-22.03-LTS-SP1(5.10.0):受影响
5.openEuler-22.03-LTS-SP2(5.10.0):受影响
6.openEuler-22.03-LTS-SP3:受影响
7.openEuler-22.03-LTS-SP4:不受影响
8.master(6.1.0):不受影响
9.openEuler-22.03-LTS-Next(5.10.0):不受影响
10.openEuler-24.03-LTS(6.6.0):不受影响
11.openEuler-24.03-LTS-Next(6.6.0):不受影响

修复是否涉及abi变化(是/否)：
  1.openEuler-20.03-LTS-SP1(4.19.90):否
2.openEuler-20.03-LTS-SP4:否
3.openEuler-22.03-LTS(5.10.0):否
4.openEuler-22.03-LTS-SP1(5.10.0):否
5.openEuler-22.03-LTS-SP2(5.10.0):否
6.openEuler-22.03-LTS-SP3:否
7.master(6.1.0):否
8.openEuler-22.03-LTS-Next(5.10.0):否
9.openEuler-24.03-LTS(6.6.0):否
10.openEuler-24.03-LTS-Next(6.6.0):否
11.openEuler-22.03-LTS-SP4:否

三、漏洞修复
安全公告链接：https://www.openeuler.org/zh/security/safety-bulletin/detail/?id=openEuler-SA-2024-1682

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