CVE-2024-56739: rtc: check if __rtc_read_time was successful in rtc_timer_do_work()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-12-29 · updated 2026-06-17
Weakness: CWE-908

Description

In the Linux kernel, the following vulnerability has been resolved: rtc: check if __rtc_read_time was successful in rtc_timer_do_work() If the __rtc_read_time call fails,, the struct rtc_time tm; may contain uninitialized data, or an illegal date/time read from the RTC hardware. When calling rtc_tm_to_ktime later, the result may be a very large value (possibly KTIME_MAX). If there are periodic timers in rtc->timerqueue, they will continually expire, may causing kernel softlockup.

Affected products

Linux kernel: from 2.6.38 before 4.19.325; from 4.20 before 5.4.287; from 5.5 before 5.10.231; from 5.11 before 5.15.174; from 5.16 before 6.1.120; from 6.2 before 6.6.64 — fixed in 4.19.325, 5.10.231, 5.15.174, 5.4.287, 6.1.120, 6.11.11

How to fix

Upgrade to a fixed version: Linux kernel 4.19.325, 5.10.231, 5.15.174, 5.4.287. Check the vendor advisory for mitigations.

References

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