| 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-2021-47569: io_uring: fail cancellation for EXITING tasks |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| io_uring: fail cancellation for EXITING tasks |
| |
| WARNING: CPU: 1 PID: 20 at fs/io_uring.c:6269 io_try_cancel_userdata+0x3c5/0x640 fs/io_uring.c:6269 |
| CPU: 1 PID: 20 Comm: kworker/1:0 Not tainted 5.16.0-rc1-syzkaller #0 |
| Workqueue: events io_fallback_req_func |
| RIP: 0010:io_try_cancel_userdata+0x3c5/0x640 fs/io_uring.c:6269 |
| Call Trace: |
| <TASK> |
| io_req_task_link_timeout+0x6b/0x1e0 fs/io_uring.c:6886 |
| io_fallback_req_func+0xf9/0x1ae fs/io_uring.c:1334 |
| process_one_work+0x9b2/0x1690 kernel/workqueue.c:2298 |
| worker_thread+0x658/0x11f0 kernel/workqueue.c:2445 |
| kthread+0x405/0x4f0 kernel/kthread.c:327 |
| ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 |
| </TASK> |
| |
| We need original task's context to do cancellations, so if it's dying |
| and the callback is executed in a fallback mode, fail the cancellation |
| attempt. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47569 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.15 with commit 89b263f6d56e683ddcf7643140271ef6e36c72b9 and fixed in 5.15.6 with commit 3d2a1e68fd9904fdc1b02f2e7d40ca47df7ba39f |
| Issue introduced in 5.15 with commit 89b263f6d56e683ddcf7643140271ef6e36c72b9 and fixed in 5.16 with commit 617a89484debcd4e7999796d693cf0b77d2519de |
| |
| 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-2021-47569 |
| 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: |
| fs/io_uring.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/3d2a1e68fd9904fdc1b02f2e7d40ca47df7ba39f |
| https://git.kernel.org/stable/c/617a89484debcd4e7999796d693cf0b77d2519de |
