CVE-2024-56547 : Detail

CVE-2024-56547

4.7
/
Medium
0.03%V4
Local
2024-12-27
14h11 +00:00
2025-05-04
09h58 +00:00
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CVE Descriptions

rcu/nocb: Fix missed RCU barrier on deoffloading

In the Linux kernel, the following vulnerability has been resolved: rcu/nocb: Fix missed RCU barrier on deoffloading Currently, running rcutorture test with torture_type=rcu fwd_progress=8 n_barrier_cbs=8 nocbs_nthreads=8 nocbs_toggle=100 onoff_interval=60 test_boost=2, will trigger the following warning: WARNING: CPU: 19 PID: 100 at kernel/rcu/tree_nocb.h:1061 rcu_nocb_rdp_deoffload+0x292/0x2a0 RIP: 0010:rcu_nocb_rdp_deoffload+0x292/0x2a0 Call Trace: ? __warn+0x7e/0x120 ? rcu_nocb_rdp_deoffload+0x292/0x2a0 ? report_bug+0x18e/0x1a0 ? handle_bug+0x3d/0x70 ? exc_invalid_op+0x18/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? rcu_nocb_rdp_deoffload+0x292/0x2a0 rcu_nocb_cpu_deoffload+0x70/0xa0 rcu_nocb_toggle+0x136/0x1c0 ? __pfx_rcu_nocb_toggle+0x10/0x10 kthread+0xd1/0x100 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x2f/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 CPU0 CPU2 CPU3 //rcu_nocb_toggle //nocb_cb_wait //rcutorture // deoffload CPU1 // process CPU1's rdp rcu_barrier() rcu_segcblist_entrain() rcu_segcblist_add_len(1); // len == 2 // enqueue barrier // callback to CPU1's // rdp->cblist rcu_do_batch() // invoke CPU1's rdp->cblist // callback rcu_barrier_callback() rcu_barrier() mutex_lock(&rcu_state.barrier_mutex); // still see len == 2 // enqueue barrier callback // to CPU1's rdp->cblist rcu_segcblist_entrain() rcu_segcblist_add_len(1); // len == 3 // decrement len rcu_segcblist_add_len(-2); kthread_parkme() // CPU1's rdp->cblist len == 1 // Warn because there is // still a pending barrier // trigger warning WARN_ON_ONCE(rcu_segcblist_n_cbs(&rdp->cblist)); cpus_read_unlock(); // wait CPU1 to comes online and // invoke barrier callback on // CPU1 rdp's->cblist wait_for_completion(&rcu_state.barrier_completion); // deoffload CPU4 cpus_read_lock() rcu_barrier() mutex_lock(&rcu_state.barrier_mutex); // block on barrier_mutex // wait rcu_barrier() on // CPU3 to unlock barrier_mutex // but CPU3 unlock barrier_mutex // need to wait CPU1 comes online // when CPU1 going online will block on cpus_write_lock The above scenario will not only trigger a WARN_ON_ONCE(), but also trigger a deadlock. Thanks to nocb locking, a second racing rcu_barrier() on an offline CPU will either observe the decremented callback counter down to 0 and spare the callback enqueue, or rcuo will observe the new callback and keep rdp->nocb_cb_sleep to false. Therefore check rdp->nocb_cb_sleep before parking to make sure no further rcu_barrier() is waiting on the rdp.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE Other No informations.

Metrics

Metrics Score Severity CVSS Vector Source
V3.1 4.7 MEDIUM CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

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.

High

successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected.

Privileges Required

This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability.

Low

The attacker requires privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.

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.

None

There is no loss of confidentiality within 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.

None

There is no loss of integrity within 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.

nvd@nist.gov

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.

Products Mentioned

Configuraton 0

Linux>>Linux_kernel >> Version From (including) 6.12 To (excluding) 6.12.2

References