| 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-2022-48950: perf: Fix perf_pending_task() UaF |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| perf: Fix perf_pending_task() UaF |
| |
| Per syzbot it is possible for perf_pending_task() to run after the |
| event is free()'d. There are two related but distinct cases: |
| |
| - the task_work was already queued before destroying the event; |
| - destroying the event itself queues the task_work. |
| |
| The first cannot be solved using task_work_cancel() since |
| perf_release() itself might be called from a task_work (____fput), |
| which means the current->task_works list is already empty and |
| task_work_cancel() won't be able to find the perf_pending_task() |
| entry. |
| |
| The simplest alternative is extending the perf_event lifetime to cover |
| the task_work. |
| |
| The second is just silly, queueing a task_work while you know the |
| event is going away makes no sense and is easily avoided by |
| re-arranging how the event is marked STATE_DEAD and ensuring it goes |
| through STATE_OFF on the way down. |
| |
| The Linux kernel CVE team has assigned CVE-2022-48950 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 5.15.84 with commit 8bffa95ac19ff27c8261904f89d36c7fcf215d59 |
| Fixed in 6.0.14 with commit 78e1317a174edbfd1182599bf76c092a2877672c |
| Fixed in 6.1 with commit 517e6a301f34613bff24a8e35b5455884f2d83d8 |
| |
| 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-2022-48950 |
| 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: |
| kernel/events/core.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/8bffa95ac19ff27c8261904f89d36c7fcf215d59 |
| https://git.kernel.org/stable/c/78e1317a174edbfd1182599bf76c092a2877672c |
| https://git.kernel.org/stable/c/517e6a301f34613bff24a8e35b5455884f2d83d8 |
