CVE-2024-57951: hrtimers: Handle CPU state correctly on hotplug
First published: Wed Feb 12 2025(Updated: )
In the Linux kernel, the following vulnerability has been resolved: hrtimers: Handle CPU state correctly on hotplug Consider a scenario where a CPU transitions from CPUHP_ONLINE to halfway through a CPU hotunplug down to CPUHP_HRTIMERS_PREPARE, and then back to CPUHP_ONLINE: Since hrtimers_prepare_cpu() does not run, cpu_base.hres_active remains set to 1 throughout. However, during a CPU unplug operation, the tick and the clockevents are shut down at CPUHP_AP_TICK_DYING. On return to the online state, for instance CFS incorrectly assumes that the hrtick is already active, and the chance of the clockevent device to transition to oneshot mode is also lost forever for the CPU, unless it goes back to a lower state than CPUHP_HRTIMERS_PREPARE once. This round-trip reveals another issue; cpu_base.online is not set to 1 after the transition, which appears as a WARN_ON_ONCE in enqueue_hrtimer(). Aside of that, the bulk of the per CPU state is not reset either, which means there are dangling pointers in the worst case. Address this by adding a corresponding startup() callback, which resets the stale per CPU state and sets the online flag. [ tglx: Make the new callback unconditionally available, remove the online modification in the prepare() callback and clear the remaining state in the starting callback instead of the prepare callback ]
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Kernel | ||
| Linux Kernel | >=4.19.302<4.20 | |
| Linux Kernel | >=5.4.264<5.4.290 | |
| Linux Kernel | >=5.10.204<5.10.234 | |
| Linux Kernel | >=5.15.143<5.15.177 | |
| Linux Kernel | >=6.1.68<6.1.127 | |
| Linux Kernel | >=6.6.7<6.6.74 | |
| Linux Kernel | >=6.7<6.12.11 | |
| Linux Kernel | =6.13-rc1 | |
| Linux Kernel | =6.13-rc2 | |
| Linux Kernel | =6.13-rc3 | |
| Linux Kernel | =6.13-rc4 | |
| Linux Kernel | =6.13-rc5 | |
| Linux Kernel | =6.13-rc6 | |
| Linux Kernel | =6.13-rc7 |
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Reference Links
- https://git.kernel.org/stable/c/95e4f62df23f4df1ce6ef897d44b8e23c260921a
- https://git.kernel.org/stable/c/14984139f1f2768883332965db566ef26db609e7
- https://git.kernel.org/stable/c/15b453db41d36184cf0ccc21e7df624014ab6a1a
- https://git.kernel.org/stable/c/3d41dbf82e10c44e53ea602398ab002baec27e75
- https://git.kernel.org/stable/c/a5cbbea145b400e40540c34816d16d36e0374fbc
- https://git.kernel.org/stable/c/38492f6ee883c7b1d33338bf531a62cff69b4b28
- https://git.kernel.org/stable/c/2f8dea1692eef2b7ba6a256246ed82c365fdc686
Frequently Asked Questions
What is the severity of CVE-2024-57951?
CVE-2024-57951 has a medium severity rating due to its impact on CPU hotplug operations in the Linux kernel.
How do I fix CVE-2024-57951?
To fix CVE-2024-57951, ensure that your Linux kernel is updated to the patched version provided by your distribution.
What systems are affected by CVE-2024-57951?
CVE-2024-57951 affects various versions of the Linux kernel that handle CPU hotplug operations.
What are the consequences of exploiting CVE-2024-57951?
Exploitation of CVE-2024-57951 could lead to incorrect state handling during CPU hotplug, potentially causing system instability.
When was CVE-2024-57951 disclosed?
CVE-2024-57951 was disclosed in 2024 as part of ongoing improvements to the Linux kernel's CPU hotplug functionality.
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