Bug 2334829 (CVE-2024-56739)

Summary: CVE-2024-56739 kernel: rtc: check if __rtc_read_time was successful in rtc_timer_do_work()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A vulnerability was found in the Linux kernel's RTC driver in the rtc_timer_do_work() function, where the __rtc_read_time call may fail. This issue results in uninitialized data in the rtc_time struct. It can lead to the generation of extremely large values, causing periodic timer failures and potentially triggering a kernel softlockup, impacting system stability.
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Description OSIDB Bzimport 2024-12-29 12:02:44 UTC 
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.
Comment 1 Avinash Hanwate 2024-12-30 03:42:16 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024122925-CVE-2024-56739-0a67@gregkh/T