CVE-2025-21851

Name of the Vulnerable Software and Affected Versions: Linux kernel (affected versions not specified)

Description: A softlockup issue in the Linux kernel has been identified, specifically in the bpf (Berkeley Packet Filter) component. This issue occurs on aarch64 kernels with a page size of 64KB, where arena htab tests cause a segmentation fault and soft lockup. The problem arises when arena map free() calls apply to existing page range() with an unaligned address, leading to a soft lockup. The issue is not observed with 4k pages on aarch64.

Recommendations: As a temporary workaround, consider disabling the arena map free() function until a patch is available. To fix the issue, round up GUARD SZ to PAGE SIZE << 1 so that the division by 2 in bpf arena get kern vm start() returns a page-aligned value. At the moment, there is no information about a newer version that contains a fix for this vulnerability.