CVE-2024-50200
05h54 +00:00
CVE の説明
maple_tree: correct tree corruption on spanning store
In the Linux kernel, the following vulnerability has been resolved: maple_tree: correct tree corruption on spanning store Patch series "maple_tree: correct tree corruption on spanning store", v3. There has been a nasty yet subtle maple tree corruption bug that appears to have been in existence since the inception of the algorithm. This bug seems far more likely to happen since commit f8d112a4e657 ("mm/mmap: avoid zeroing vma tree in mmap_region()"), which is the point at which reports started to be submitted concerning this bug. We were made definitely aware of the bug thanks to the kind efforts of Bert Karwatzki who helped enormously in my being able to track this down and identify the cause of it. The bug arises when an attempt is made to perform a spanning store across two leaf nodes, where the right leaf node is the rightmost child of the shared parent, AND the store completely consumes the right-mode node. This results in mas_wr_spanning_store() mitakenly duplicating the new and existing entries at the maximum pivot within the range, and thus maple tree corruption. The fix patch corrects this by detecting this scenario and disallowing the mistaken duplicate copy. The fix patch commit message goes into great detail as to how this occurs. This series also includes a test which reliably reproduces the issue, and asserts that the fix works correctly. Bert has kindly tested the fix and confirmed it resolved his issues. Also Mikhail Gavrilov kindly reported what appears to be precisely the same bug, which this fix should also resolve. This patch (of 2): There has been a subtle bug present in the maple tree implementation from its inception. This arises from how stores are performed - when a store occurs, it will overwrite overlapping ranges and adjust the tree as necessary to accommodate this. A range may always ultimately span two leaf nodes. In this instance we walk the two leaf nodes, determine which elements are not overwritten to the left and to the right of the start and end of the ranges respectively and then rebalance the tree to contain these entries and the newly inserted one. This kind of store is dubbed a 'spanning store' and is implemented by mas_wr_spanning_store(). In order to reach this stage, mas_store_gfp() invokes mas_wr_preallocate(), mas_wr_store_type() and mas_wr_walk() in turn to walk the tree and update the object (mas) to traverse to the location where the write should be performed, determining its store type. When a spanning store is required, this function returns false stopping at the parent node which contains the target range, and mas_wr_store_type() marks the mas->store_type as wr_spanning_store to denote this fact. When we go to perform the store in mas_wr_spanning_store(), we first determine the elements AFTER the END of the range we wish to store (that is, to the right of the entry to be inserted) - we do this by walking to the NEXT pivot in the tree (i.e. r_mas.last + 1), starting at the node we have just determined contains the range over which we intend to write. We then turn our attention to the entries to the left of the entry we are inserting, whose state is represented by l_mas, and copy these into a 'big node', which is a special node which contains enough slots to contain two leaf node's worth of data. We then copy the entry we wish to store immediately after this - the copy and the insertion of the new entry is performed by mas_store_b_node(). After this we copy the elements to the right of the end of the range which we are inserting, if we have not exceeded the length of the node (i.e. r_mas.offset <= r_mas.end). Herein lies the bug - under very specific circumstances, this logic can break and corrupt the maple tree. Consider the following tree: Height 0 Root Node / \ pivot = 0xffff / \ pivot = ULONG_MAX / ---truncated---CVE の情報
関連する弱点
| 弱点名 | 出典 | |
|---|---|---|
| 情報がありません。 |
メトリクス
| メトリクス | スコア | 深刻度 | CVSS ベクター | 出典 |
|---|---|---|---|---|
| V3.1 | 7.8 | HIGH |
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
詳細情報
Base: Exploitabilty MetricsThe 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. 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 MetricsThe 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 MetricsThe 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. High There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server. Integrity Impact This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. High There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to 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 MetricsThe 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 MetricsThese 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. |
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| V3.1 | 5.5 | MEDIUM |
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
詳細情報
Base: Exploitabilty MetricsThe 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. 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 MetricsThe 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 MetricsThe 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 MetricsThe 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 MetricsThese 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 |
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