CVE-2025-40143
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-11-12

Last updated on: 2025-11-12

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: bpf: dont report verifier bug for missing bpf_scc_visit on speculative path Syzbot generated a program that triggers a verifier_bug() call in maybe_exit_scc(). maybe_exit_scc() assumes that, when called for a state with insn_idx in some SCC, there should be an instance of struct bpf_scc_visit allocated for that SCC. Turns out the assumption does not hold for speculative execution paths. See example in the next patch. maybe_scc_exit() is called from update_branch_counts() for states that reach branch count of zero, meaning that path exploration for a particular path is finished. Path exploration can finish in one of three ways: a. Verification error is found. In this case, update_branch_counts() is called only for non-speculative paths. b. Top level BPF_EXIT is reached. Such instructions are never a part of an SCC, so compute_scc_callchain() in maybe_scc_exit() will return false, and maybe_scc_exit() will return early. c. A checkpoint is reached and matched. Checkpoints are created by is_state_visited(), which calls maybe_enter_scc(), which allocates bpf_scc_visit instances for checkpoints within SCCs. Hence, for non-speculative symbolic execution paths, the assumption still holds: if maybe_scc_exit() is called for a state within an SCC, bpf_scc_visit instance must exist. This patch removes the verifier_bug() call for speculative paths.
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Meta Information
Published
2025-11-12
Last Modified
2025-11-12
Generated
2026-05-07
AI Q&A
2025-11-13
EPSS Evaluated
2026-05-05
NVD
CVE-2025-40143
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
Helpful Resources
Exploitability
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CWE ID Description
CWE-UNKNOWN
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AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability involves the Linux kernel's BPF verifier incorrectly reporting a bug (verifier_bug) during speculative execution paths. The verifier assumed that a certain data structure (bpf_scc_visit) would always be allocated for states within strongly connected components (SCCs), but this assumption does not hold for speculative paths. As a result, the verifier could trigger an erroneous bug report. The patch removes this incorrect bug report for speculative paths, fixing the issue.


How can this vulnerability impact me? :

This vulnerability could cause the BPF verifier in the Linux kernel to incorrectly report bugs during speculative execution, potentially leading to false positives in verification. This might affect the reliability of BPF program verification and could impact system stability or debugging processes, but it does not indicate a direct security compromise or exploit.


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