Linux Kernel up to 6.19.3 on ARM32 clocksource timer-sp804 read_current_timer uninitialized pointer

Summaryinfo

A vulnerability categorized as critical has been discovered in Linux Kernel up to 6.19.3 on ARM32. The impacted element is the function read_current_timer of the file clocksource/drivers/timer-sp804 of the component clocksource. The manipulation results in uninitialized pointer. This vulnerability is identified as CVE-2026-46257. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.19.3 on ARM32. Affected is the function read_current_timer of the file clocksource/drivers/timer-sp804 of the component clocksource. The manipulation with an unknown input leads to a uninitialized pointer vulnerability. CWE is classifying the issue as CWE-824. The product accesses or uses a pointer that has not been initialized. The impact remains unknown. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: clocksource/drivers/timer-sp804: Fix an Oops when read_current_timer is called on ARM32 platforms where the SP804 is not registered as the sched_clock. On SP804, the delay timer shares the same clkevt instance with sched_clock. On some platforms, when sp804_clocksource_and_sched_clock_init is called with use_sched_clock not set to 1, sched_clkevt is not properly initialized. However, sp804_register_delay_timer is invoked unconditionally, and read_current_timer() subsequently calls sp804_read on an uninitialized sched_clkevt, leading to a kernel Oops when accessing sched_clkevt->value. Declare a dedicated clkevt instance exclusively for delay timer, instead of sharing the same clkevt with sched_clock. This ensures that read_current_timer continues to work correctly regardless of whether SP804 is selected as the sched_clock.

The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2026-46257 since 05/13/2026. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 06/03/2026).

Upgrading to version 6.19.4 eliminates this vulnerability. Applying the patch 693b0b594b0f278bafa784984129c0c0f988e352/694921a93f3e3621e067afc545cedf6fe3b234a9 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.19.0
• 6.19.1
• 6.19.2
• 6.19.3

License

• open-source

Website

• Vendor: https://www.kernel.org/

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