UBUNTU-CVE-2024-57951
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 ]
02 / AFFECTED SOFTWARE
Affected packages
50 explicit affected versions
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13 explicit affected versions
56 explicit affected versions
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3 explicit affected versions
13 explicit affected versions
26 explicit affected versions
45 explicit affected versions
14 explicit affected versions
38 explicit affected versions
53 explicit affected versions
9 explicit affected versions
51 explicit affected versions
11 explicit affected versions
17 explicit affected versions
7 explicit affected versions
62 explicit affected versions
60 explicit affected versions
13 explicit affected versions
43 explicit affected versions
58 explicit affected versions
17 explicit affected versions
10 explicit affected versions
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22 explicit affected versions
14 explicit affected versions
92 explicit affected versions
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78 explicit affected versions
11 explicit affected versions
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03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
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 ]
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/2f8dea1692eef2b7ba6a256246ed82c365fdc686
- https://git.kernel.org/stable/c/14984139f1f2768883332965db566ef26db609e7
- https://git.kernel.org/stable/c/15b453db41d36184cf0ccc21e7df624014ab6a1a
- https://git.kernel.org/stable/c/2f8dea1692eef2b7ba6a256246ed82c365fdc686
- https://git.kernel.org/stable/c/38492f6ee883c7b1d33338bf531a62cff69b4b28
- https://git.kernel.org/stable/c/3d41dbf82e10c44e53ea602398ab002baec27e75
- https://git.kernel.org/stable/c/95e4f62df23f4df1ce6ef897d44b8e23c260921a
- https://git.kernel.org/stable/c/a5cbbea145b400e40540c34816d16d36e0374fbc
- https://ubuntu.com/security/CVE-2024-57951
- https://ubuntu.com/security/notices/USN-7387-1
- https://ubuntu.com/security/notices/USN-7387-2
- https://ubuntu.com/security/notices/USN-7387-3
- https://ubuntu.com/security/notices/USN-7388-1
- https://ubuntu.com/security/notices/USN-7389-1
- https://ubuntu.com/security/notices/USN-7390-1
- https://ubuntu.com/security/notices/USN-7391-1
- https://ubuntu.com/security/notices/USN-7392-1
- https://ubuntu.com/security/notices/USN-7392-2
- https://ubuntu.com/security/notices/USN-7392-3
- https://ubuntu.com/security/notices/USN-7392-4
- https://ubuntu.com/security/notices/USN-7393-1
- https://ubuntu.com/security/notices/USN-7401-1
- https://ubuntu.com/security/notices/USN-7407-1
- https://ubuntu.com/security/notices/USN-7413-1
- https://ubuntu.com/security/notices/USN-7421-1
- https://ubuntu.com/security/notices/USN-7445-1
- https://ubuntu.com/security/notices/USN-7448-1
- https://ubuntu.com/security/notices/USN-7458-1
- https://ubuntu.com/security/notices/USN-7459-1
- https://ubuntu.com/security/notices/USN-7459-2
- https://ubuntu.com/security/notices/USN-7463-1
- https://ubuntu.com/security/notices/USN-7539-1
- https://ubuntu.com/security/notices/USN-7540-1
- https://ubuntu.com/security/notices/USN-7595-1
- https://ubuntu.com/security/notices/USN-7595-2
- https://ubuntu.com/security/notices/USN-7595-3
- https://ubuntu.com/security/notices/USN-7595-4
- https://ubuntu.com/security/notices/USN-7595-5
- https://ubuntu.com/security/notices/USN-7596-1
- https://ubuntu.com/security/notices/USN-7596-2
- https://ubuntu.com/security/notices/USN-7653-1
- https://www.cve.org/CVERecord?id=CVE-2024-57951