CVE-2025-39737 — mm/kmemleak: avoid soft lockup in __kmemleak_do_cleanup()

Affected: Linux, Siemens SIMATIC CN 4100

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.

USN-7909-1 — linux, linux-aws, linux-aws-5.15, linux-gcp-5.15, linux-hwe-5.15, linux-ibm, linux-ibm-5.15, linux-intel-iotg, linux-in…

Affected: Ubuntu:Pro:20.04:LTS: linux-aws-5.15, Ubuntu:Pro:20.04:LTS: linux-gcp-5.15, Ubuntu:Pro:20.04:LTS: linux-hwe-5.15, Ubuntu:Pro:20.04:LTS: linux-ibm-5.15, Ubuntu:Pro:20.04:LTS: linux-intel-iotg-5.15, Ubuntu:Pro:20.04:LTS: linux-lowlatency-hwe-5.15, Ubuntu:Pro:20.04:LTS: linux-nvidia-tegra-5.15, Ubuntu:Pro:20.04:LTS: linux-oracle-5.15, Ubuntu:22.04:LTS: linux, Ubuntu:22.04:LTS: linux-aws and 8 more

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - ARM32 architecture; - ARM64 architecture; - MIPS architecture; - PowerPC architecture; - RISC-V architecture; - S390 architecture; - x86 architecture; - Block layer subsystem; - ACPI drivers; - ATM drivers; - DRBD Distributed Replicated Block Device drivers; - Bus devices; - Clock framework and drivers; - Data acquisition framework and drivers; - Hardware crypto device drivers; - Device frequency scaling framework; - Buffer Sharing and Synchronization framework; - DMA engine subsystem; - ARM SCMI message protocol; - GPU drivers; - HID subsystem; - Hardware monitoring drivers; - I2C subsystem; - I3C subsystem; - IIO subsystem; - InfiniBand drivers; - Input Device core drivers; - IOMMU subsystem; - Media drivers; - Network drivers; - Mellanox network drivers; - PCI subsystem; - PCCARD (PCMCIA/CardBus) bus subsystem; - PHY drivers; - Power supply drivers; - Voltage and Current Regulator drivers; - SCSI subsystem; - ASPEED SoC drivers; - QCOM SoC drivers; - small TFT LCD display modules; - Trusted Execution Environment drivers; - TTY drivers; - UFS subsystem; - USB core drivers; - DesignWare USB3 driver; - USB Gadget drivers; - Framebuffer layer; - BTRFS file system; - File systems infrastructure; - EF…

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CVE-2025-39737 — mm/kmemleak: avoid soft lockup in __kmemleak_do_cleanup()

USN-7909-1 — linux, linux-aws, linux-aws-5.15, linux-gcp-5.15, linux-hwe-5.15, linux-ibm, linux-ibm-5.15, linux-intel-iotg, linux-in…