| 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-2024-49866: tracing/timerlat: Fix a race during cpuhp processing |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| tracing/timerlat: Fix a race during cpuhp processing |
| |
| There is another found exception that the "timerlat/1" thread was |
| scheduled on CPU0, and lead to timer corruption finally: |
| |
| ``` |
| ODEBUG: init active (active state 0) object: ffff888237c2e108 object type: hrtimer hint: timerlat_irq+0x0/0x220 |
| WARNING: CPU: 0 PID: 426 at lib/debugobjects.c:518 debug_print_object+0x7d/0xb0 |
| Modules linked in: |
| CPU: 0 UID: 0 PID: 426 Comm: timerlat/1 Not tainted 6.11.0-rc7+ #45 |
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 |
| RIP: 0010:debug_print_object+0x7d/0xb0 |
| ... |
| Call Trace: |
| <TASK> |
| ? __warn+0x7c/0x110 |
| ? debug_print_object+0x7d/0xb0 |
| ? report_bug+0xf1/0x1d0 |
| ? prb_read_valid+0x17/0x20 |
| ? handle_bug+0x3f/0x70 |
| ? exc_invalid_op+0x13/0x60 |
| ? asm_exc_invalid_op+0x16/0x20 |
| ? debug_print_object+0x7d/0xb0 |
| ? debug_print_object+0x7d/0xb0 |
| ? __pfx_timerlat_irq+0x10/0x10 |
| __debug_object_init+0x110/0x150 |
| hrtimer_init+0x1d/0x60 |
| timerlat_main+0xab/0x2d0 |
| ? __pfx_timerlat_main+0x10/0x10 |
| kthread+0xb7/0xe0 |
| ? __pfx_kthread+0x10/0x10 |
| ret_from_fork+0x2d/0x40 |
| ? __pfx_kthread+0x10/0x10 |
| ret_from_fork_asm+0x1a/0x30 |
| </TASK> |
| ``` |
| |
| After tracing the scheduling event, it was discovered that the migration |
| of the "timerlat/1" thread was performed during thread creation. Further |
| analysis confirmed that it is because the CPU online processing for |
| osnoise is implemented through workers, which is asynchronous with the |
| offline processing. When the worker was scheduled to create a thread, the |
| CPU may has already been removed from the cpu_online_mask during the offline |
| process, resulting in the inability to select the right CPU: |
| |
| T1 | T2 |
| [CPUHP_ONLINE] | cpu_device_down() |
| osnoise_hotplug_workfn() | |
| | cpus_write_lock() |
| | takedown_cpu(1) |
| | cpus_write_unlock() |
| [CPUHP_OFFLINE] | |
| cpus_read_lock() | |
| start_kthread(1) | |
| cpus_read_unlock() | |
| |
| To fix this, skip online processing if the CPU is already offline. |
| |
| The Linux kernel CVE team has assigned CVE-2024-49866 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.14 with commit c8895e271f7994a3ecb13b8a280e39aa53879545 and fixed in 5.15.168 with commit 322920b53dc11f9c2b33397eb3ae5bc6a175b60d |
| Issue introduced in 5.14 with commit c8895e271f7994a3ecb13b8a280e39aa53879545 and fixed in 6.1.113 with commit ce25f33ba89d6eefef64157655d318444580fa14 |
| Issue introduced in 5.14 with commit c8895e271f7994a3ecb13b8a280e39aa53879545 and fixed in 6.6.55 with commit a6e9849063a6c8f4cb2f652a437e44e3ed24356c |
| Issue introduced in 5.14 with commit c8895e271f7994a3ecb13b8a280e39aa53879545 and fixed in 6.10.14 with commit a0d9c0cd5856191e095cf43a2e141b73945b7716 |
| Issue introduced in 5.14 with commit c8895e271f7994a3ecb13b8a280e39aa53879545 and fixed in 6.11.3 with commit f72b451dc75578f644a3019c1489e9ae2c14e6c4 |
| Issue introduced in 5.14 with commit c8895e271f7994a3ecb13b8a280e39aa53879545 and fixed in 6.12 with commit 829e0c9f0855f26b3ae830d17b24aec103f7e915 |
| |
| 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-2024-49866 |
| 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/trace/trace_osnoise.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/322920b53dc11f9c2b33397eb3ae5bc6a175b60d |
| https://git.kernel.org/stable/c/ce25f33ba89d6eefef64157655d318444580fa14 |
| https://git.kernel.org/stable/c/a6e9849063a6c8f4cb2f652a437e44e3ed24356c |
| https://git.kernel.org/stable/c/a0d9c0cd5856191e095cf43a2e141b73945b7716 |
| https://git.kernel.org/stable/c/f72b451dc75578f644a3019c1489e9ae2c14e6c4 |
| https://git.kernel.org/stable/c/829e0c9f0855f26b3ae830d17b24aec103f7e915 |
