CVE Catalog

CVE-2025-39737

MediumCVSS 5.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.18%

7th percentile - higher than 7% of all known CVEs

Summary

In the Linux kernel, kmemleak cleanup removes objects one by one in a workqueue loop, which with many objects (e.g. 40,000) and a slow debug kernel can trigger a soft lockup. The fix adds periodic cond_resched() calls in the loop.

Risk Assessment

A soft lockup can stall a kernel thread for an extended time and degrade system responsiveness, especially on a debug kernel with kmemleak enabled.

Recommendation

Update the Linux kernel to a version containing the fix that adds cond_resched() in the kmemleak cleanup loop.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: mm/kmemleak: avoid soft lockup in __kmemleak_do_cleanup() A soft lockup warning was observed on a relative small system x86-64 system with 16 GB of memory when running a debug kernel with kmemleak enabled. watchdog: BUG: soft lockup - CPU#8 stuck for 33s! [kworker/8:1:134] The test system was running a workload with hot unplug happening in parallel. Then kemleak decided to disable itself due to its inability to allocate more kmemleak objects. The debug kernel has its CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE set to 40,000. The soft lockup happened in kmemleak_do_cleanup() when the existing kmemleak objects were being removed and deleted one-by-one in a loop via a workqueue. In this particular case, there are at least 40,000 objects that need to be processed and given the slowness of a debug kernel and the fact that a raw_spinlock has to be acquired and released in __delete_object(), it could take a while to properly handle all these objects. As kmemleak has been disabled in this case, the object removal and deletion process can be further optimized as locking isn't really needed. However, it is probably not worth the effort to optimize for such an edge case that should rarely happen. So the simple solution is to call cond_resched() at periodic interval in the iteration loop to avoid soft lockup.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS