Spectre V2

Spectre v2 is a software vulnerability that arises from an incorrect implementation of its simultaneous multithreading (SMT) mitigations, particularly in relation to calling prctl with PR_SET_SPECULATION_CTRL. This flaw in the software design or execution allows for potential exploitation by malicious entities. A similar vulnerability, Spectre-BHB, operates on a comparable principle, wherein the malicious code utilizes the shared branch history stored in the CPU Branch History Buffer (BHB) to influence mispredicted branches within the victim's hardware context. Several major tech companies have responded to these vulnerabilities and their potential implications. Intel has committed to addressing the issue through software guidance, while AMD maintains that existing Spectre v2 mitigations are effective against another exploit known as SLAM. Arm, a leading technology provider, published a security advisory assuring customers that existing countermeasures for Spectre v2 and Spectre BHI should adequately protect against potential exploitations. In response to the disclosure by researchers, both Arm and AMD have reiterated their stance on the effectiveness of current Spectre v2 mitigations against the SLAM attack described by the VUSec research group. Arm has further issued an advisory explaining that no additional action is required in response to the SLAM exploit due to their existing protections against Spectre v2 and Spectre-BHB. Meanwhile, AMD did not provide any new guidance or updates to lower the risk, reinforcing their confidence in existing mitigations. Intel plans to provide software guidance prior to releasing processors which support a similar exploit called LAM.