CVE Descriptions

In the Linux kernel, the following vulnerability has been resolved: MIPS: Work around LLVM bug when gp is used as global register variable On MIPS, __current_thread_info is defined as global register variable locating in $gp, and is simply assigned with new address during kernel relocation. This however is broken with LLVM, which always restores $gp if it finds $gp is clobbered in any form, including when intentionally through a global register variable. This is against GCC's documentation[1], which requires a callee-saved register used as global register variable not to be restored if it's clobbered. As a result, $gp will continue to point to the unrelocated kernel after the epilog of relocate_kernel(), leading to an early crash in init_idle, [ 0.000000] CPU 0 Unable to handle kernel paging request at virtual address 0000000000000000, epc == ffffffff81afada8, ra == ffffffff81afad90 [ 0.000000] Oops[#1]: [ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper Tainted: G W 6.19.0-rc5-00262-gd3eeb99bbc99-dirty #188 VOLUNTARY [ 0.000000] Tainted: [W]=WARN [ 0.000000] Hardware name: loongson,loongson64v-4core-virtio [ 0.000000] $ 0 : 0000000000000000 0000000000000000 0000000000000001 0000000000000000 [ 0.000000] $ 4 : ffffffff80b80ec0 ffffffff80b53d48 0000000000000000 00000000000f4240 [ 0.000000] $ 8 : 0000000000000100 ffffffff81d82f80 ffffffff81d82f80 0000000000000001 [ 0.000000] $12 : 0000000000000000 ffffffff81776f58 00000000000005da 0000000000000002 [ 0.000000] $16 : ffffffff80b80e40 0000000000000000 ffffffff80b81614 9800000005dfbe80 [ 0.000000] $20 : 00000000540000e0 ffffffff81980000 0000000000000000 ffffffff80f81c80 [ 0.000000] $24 : 0000000000000a26 ffffffff8114fb90 [ 0.000000] $28 : ffffffff80b50000 ffffffff80b53d40 0000000000000000 ffffffff81afad90 [ 0.000000] Hi : 0000000000000000 [ 0.000000] Lo : 0000000000000000 [ 0.000000] epc : ffffffff81afada8 init_idle+0x130/0x270 [ 0.000000] ra : ffffffff81afad90 init_idle+0x118/0x270 [ 0.000000] Status: 540000e2 KX SX UX KERNEL EXL [ 0.000000] Cause : 00000008 (ExcCode 02) [ 0.000000] BadVA : 0000000000000000 [ 0.000000] PrId : 00006305 (ICT Loongson-3) [ 0.000000] Process swapper (pid: 0, threadinfo=(____ptrval____), task=(____ptrval____), tls=0000000000000000) [ 0.000000] Stack : 9800000005dfbf00 ffffffff8178e950 0000000000000000 0000000000000000 [ 0.000000] 0000000000000000 ffffffff81970000 000000000000003f ffffffff810a6528 [ 0.000000] 0000000000000001 9800000005dfbe80 9800000005dfbf00 ffffffff81980000 [ 0.000000] ffffffff810a6450 ffffffff81afb6c0 0000000000000000 ffffffff810a2258 [ 0.000000] ffffffff81d82ec8 ffffffff8198d010 ffffffff81b67e80 ffffffff8197dd98 [ 0.000000] ffffffff81d81c80 ffffffff81930000 0000000000000040 0000000000000000 [ 0.000000] 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 0.000000] 0000000000000000 000000000000009e ffffffff9fc01000 0000000000000000 [ 0.000000] 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 0.000000] 0000000000000000 ffffffff81ae86dc ffffffff81b3c741 0000000000000002 [ 0.000000] ... [ 0.000000] Call Trace: [ 0.000000] [] init_idle+0x130/0x270 [ 0.000000] [] sched_init+0x5c8/0x6c0 [ 0.000000] [] start_kernel+0x27c/0x7a8 This bug has been reported to LLVM[2] and affects version from (at least) 18 to 21. Let's work around this by using inline assembly to assign $gp before a fix is widely available.

CVE Informations

Related Weaknesses

CWE-ID	Weakness Name	Source
CWE Other	No informations.

Metrics

Metrics	Score	Severity	CVSS Vector	Source
V3.1	7.3	HIGH	CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H More informations Base: Exploitabilty Metrics The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component. Attack Vector This metric reflects the context by which vulnerability exploitation is possible. Local The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Attack Complexity This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. Low Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component. Privileges Required This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. None The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack. User Interaction This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable component. None The vulnerable system can be exploited without interaction from any user. Base: Scope Metrics The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope. Scope Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs. Unchanged An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority. Base: Impact Metrics The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve. Confidentiality Impact This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability. Low There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component. Integrity Impact This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Low Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component. Availability Impact This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. High There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable). Temporal Metrics The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence in the description of a vulnerability. Environmental Metrics These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.	416baaa9-dc9f-4396-8d5f-8c081fb06d67

EPSS

EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.

EPSS Score

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

EPSS Percentile

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.

EPSS First.org