CVE-2024-50032: rcu/nocb: Fix rcuog wake-up from offline softirq
First published: Mon Oct 21 2024(Updated: )
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().
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Kernel | >=6.6.54<6.6.57 | |
| Linux Kernel | >=6.10.13<6.11 | |
| Linux Kernel | >=6.11.2<6.11.4 | |
| Linux Kernel | =6.1.113 | |
| Linux Kernel | =6.12-rc1 | |
| Linux Kernel | =6.12-rc2 | |
| debian/linux | <=6.1.129-1<=6.1.133-1 | 5.10.223-1 5.10.234-1 6.12.22-1 |
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Reference Links
- https://git.kernel.org/stable/c/84a5feebba10354c683983f5f1372a144225e4c2
- https://git.kernel.org/stable/c/e66b1e01f2eb3209d08122572f41f7838b79540d
- https://git.kernel.org/stable/c/f7345ccc62a4b880cf76458db5f320725f28e400
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-50032
- https://nvd.nist.gov/vuln/detail/CVE-2024-50032
- https://launchpad.net/bugs/cve/CVE-2024-50032
- https://security-tracker.debian.org/tracker/CVE-2024-50032
- https://ubuntu.com/security/CVE-2024-50032
- https://git.kernel.org/linus/f7345ccc62a4b880cf76458db5f320725f28e400
Frequently Asked Questions
What is the severity of CVE-2024-50032?
CVE-2024-50032 is rated as a medium severity vulnerability in the Linux kernel.
How do I fix CVE-2024-50032?
To fix CVE-2024-50032, update your Linux kernel to a version that includes the patch for this vulnerability.
Which versions of the Linux kernel are affected by CVE-2024-50032?
CVE-2024-50032 affects Linux kernel versions between 6.6.54 and 6.6.57, as well as several other specified versions.
What type of vulnerability is CVE-2024-50032?
CVE-2024-50032 is a race condition vulnerability related to the rcu/nocb subsystem in the Linux kernel.
Can CVE-2024-50032 lead to system crashes?
Yes, CVE-2024-50032 could potentially lead to system instability or crashes due to improper handling of callback enqueuing.
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