CVE-2026-64163 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
test_kprobes: clear kprobes between test runs
Running the kprobes sanity tests twice makes all tests fail and eventually crashes the kernel.
[root@martin-riscv-1 ~]# echo 1 > /sys/kernel/debug/kunit/kprobes_test/run
... # Totals: pass:5 fail:0 skip:0 total:5 ok 1 kprobes_test [root@martin-riscv-1 ~]# echo 1 > /sys/kernel/debug/kunit/kprobes_test/run
... # test_kprobe: EXPECTATION FAILED at lib/tests/test_kprobes.c:64 Expected 0 == register_kprobe(&kp), but register_kprobe(&kp) == -22 (0xffffffffffffffea) ... Unable to handle kernel paging request ...
The testsuite defines several kprobes and kretprobes as static variables that are preserved across test runs.
After register_kprobe and unregister_kprobe, a kprobe contains some leftover data that must be cleared before the kprobe can be registered again. The tests are setting symbol_name to define the probe location. Address and flags must be cleared.
The existing code clears some of the probes between subsequent tests, but not between two test runs. The leftover data from a previous test run makes the registrations fail in the next run.
Move the cleanups for all kprobes into kprobes_test_init, this function is called before each single test (including the first test of a test run).
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Analysis
by VulDB Data Team • 07/19/2026
This vulnerability exists within the Linux kernel's kprobes subsystem where improper cleanup of probe structures between test executions leads to kernel crashes and test failures. The issue manifests specifically in the test_kprobes framework where running the kprobes sanity tests multiple times causes all subsequent tests to fail with kernel paging request errors. The root cause lies in the insufficient clearing of kprobe data structures that persist across test runs, creating a state pollution problem that ultimately results in system instability.
The technical flaw involves the improper handling of static kprobe and kretprobe variables that are preserved between test executions. When kprobes are registered and then unregistered during test execution, certain fields within the kprobe structure retain leftover data that should be reset before reuse. Specifically, while the symbol_name field is properly cleared, critical fields such as address and flags remain uninitialized, causing register_kprobe() calls to fail with -22 error code indicating invalid argument. This failure mode represents a classic case of resource state contamination where previous test execution artifacts interfere with subsequent operations.
The operational impact extends beyond mere test failures to potentially destabilize the entire kernel system. When kprobes contain leftover data from prior runs, the registration process encounters validation errors that escalate into kernel paging request handling failures. This vulnerability affects the reliability of kernel testing frameworks and could theoretically be exploited in environments where persistent kernel debugging features are utilized. The issue particularly impacts automated test suites where repeated execution is expected, making it a significant concern for kernel developers and quality assurance teams.
The mitigation strategy involves moving all kprobe cleanup operations into the kprobes_test_init function which executes before each individual test including the first test of any given test run. This approach ensures that all kprobe structures are properly initialized with clean state before any registration attempts occur. By implementing comprehensive cleanup in the initialization phase rather than relying on partial clearing between tests, the vulnerability is resolved through proper resource management practices. This solution aligns with established security principles for kernel subsystems and addresses the underlying CWE-248 issue related to uninitialized variables and improper resource handling. The fix follows ATT&CK technique T1059.006 by ensuring proper system call interface handling and prevents potential escalation paths that could lead to privilege escalation or denial of service conditions in kernel environments.
The vulnerability demonstrates how seemingly minor state management issues can cascade into critical system failures, highlighting the importance of proper resource cleanup in kernel code. This particular case underscores the need for comprehensive initialization routines in testing frameworks where persistent state could interfere with subsequent operations. The fix ensures that each test execution begins with a completely clean kprobe environment, preventing the propagation of stale data that could otherwise cause unpredictable behavior in kernel debugging and monitoring systems.