| 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-2024-50032: rcu/nocb: Fix rcuog wake-up from offline softirq |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| rcu/nocb: Fix rcuog wake-up from offline softirq |
| |
| After a CPU has set itself offline and before it eventually calls |
| rcutree_report_cpu_dead(), there are still opportunities for callbacks |
| to be enqueued, for example from a softirq. When that happens on NOCB, |
| the rcuog wake-up is deferred through an IPI to an online CPU in order |
| not to call into the scheduler and risk arming the RT-bandwidth after |
| hrtimers have been migrated out and disabled. |
| |
| But performing a synchronized IPI from a softirq is buggy as reported in |
| the following scenario: |
| |
| WARNING: CPU: 1 PID: 26 at kernel/smp.c:633 smp_call_function_single |
| Modules linked in: rcutorture torture |
| CPU: 1 UID: 0 PID: 26 Comm: migration/1 Not tainted 6.11.0-rc1-00012-g9139f93209d1 #1 |
| Stopper: multi_cpu_stop+0x0/0x320 <- __stop_cpus+0xd0/0x120 |
| RIP: 0010:smp_call_function_single |
| <IRQ> |
| swake_up_one_online |
| __call_rcu_nocb_wake |
| __call_rcu_common |
| ? rcu_torture_one_read |
| call_timer_fn |
| __run_timers |
| run_timer_softirq |
| handle_softirqs |
| irq_exit_rcu |
| ? tick_handle_periodic |
| sysvec_apic_timer_interrupt |
| </IRQ> |
| |
| Fix this with forcing deferred rcuog wake up through the NOCB timer when |
| the CPU is offline. The actual wake up will happen from |
| rcutree_report_cpu_dead(). |
| |
| The Linux kernel CVE team has assigned CVE-2024-50032 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.6.54 with commit 9b52ee18f6d2f0e845b0dd5ba35edc02ba318827 and fixed in 6.6.57 with commit 84a5feebba10354c683983f5f1372a144225e4c2 |
| Issue introduced in 6.11.2 with commit 00a611229bfad075660181c53e054ff544d3ac34 and fixed in 6.11.4 with commit e66b1e01f2eb3209d08122572f41f7838b79540d |
| Issue introduced in 6.1.113 with commit ec2777e57f2f548702b147c6e5cc088079bd93ca |
| Issue introduced in 6.10.13 with commit bbeaae6f79b2923cf8b8f191d039b19f11adf045 |
| |
| 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-2024-50032 |
| 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/rcu/tree_nocb.h |
| |
| |
| 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/84a5feebba10354c683983f5f1372a144225e4c2 |
| https://git.kernel.org/stable/c/e66b1e01f2eb3209d08122572f41f7838b79540d |
| https://git.kernel.org/stable/c/f7345ccc62a4b880cf76458db5f320725f28e400 |
