Linux Kernel Vulnerability in Networking Component Affecting Kernel Functionality

CVE-2025-21857

Summary

A vulnerability has been identified in the Linux kernel networking stack, particularly within the classful queuing framework. An error in error handling during the allocation process can lead to a NULL pointer dereference. When the function tcf_exts_miss_cookie_base_alloc() erroneously treats a successful allocation returning a '1' as a failure, this misleading output can propagate through several function calls. Ultimately, this results in the kernel attempting to dereference a null pointer, leading to potential crashes or instability. Proper validation measures should be ensured to prevent such erroneous behaviors.

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