CVE-2026-80734 : 상세 정보

CVE-2026-80734

8.8
/
높음
2026-09-03
13h06 +00:00
Network
2026-10-21
13h19 +00:00
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CVE 설명

In the Linux kernel, the following vulnerability has been resolved: btrfs: initialize inode mapping flags for cached inodes [BUG] When running generic/795 with 8K block size, 4K page size, the test always fails, triggering some ASSERT()s related to folio size: 795 (241074): drop_caches: 3 assertion failed: IS_ALIGNED(start, blocksize) && IS_ALIGNED(end + 1, blocksize), in extent_io.c:1404 (blocksize=8192 root=262 ino=258 start=16826368 end=16830463 mapping min order=0) ------------[ cut here ]------------ kernel BUG at extent_io.c:1404! Oops: invalid opcode: 0000 [#1] SMP CPU: 8 UID: 0 PID: 241105 Comm: fsstress Tainted: G OE 7.2.0-rc5-custom+ #442 PREEMPT(full) f4bfb352566f3949f29c233ce6f735050a03b245 Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022 RIP: 0010:assert_folio_range.cold+0x3d/0x3f [btrfs] Call Trace: btrfs_read_folio+0x9e/0x170 [btrfs 4cd1dd93b341b8ef766643f9512f4a86259567a3] prepare_one_folio.constprop.0+0x104/0x2a0 [btrfs 4cd1dd93b341b8ef766643f9512f4a86259567a3] btrfs_buffered_write+0x285/0xa50 [btrfs 4cd1dd93b341b8ef766643f9512f4a86259567a3] btrfs_do_write_iter+0x1aa/0x210 [btrfs 4cd1dd93b341b8ef766643f9512f4a86259567a3] iter_file_splice_write+0x31a/0x540 direct_splice_actor+0x53/0x170 splice_direct_to_actor+0xe9/0x240 do_splice_direct+0x76/0xb0 vfs_copy_file_range+0x1fd/0x630 __x64_sys_copy_file_range+0xf9/0x220 do_syscall_64+0xe1/0x790 entry_SYSCALL_64_after_hwframe+0x4b/0x53 ---[ end trace 0000000000000000 ]--- The ASSERT() itself is added by a later patch. The crash is triggered with that new debug patch, and without this fix. [CAUSE] In the above case, the start 16826368 is properly 8K aligned, but the end (16830463 + 1) is not 8K aligned. Furthermore the mapping's minimal folio order is 0, not the expected 1 for 8K block size with 4K page size. So this means some inodes do not have btrfs_set_inode_mapping_order() called on it. The missing btrfs_set_inode_mapping_order() call happens for cached inodes, through the following events: - btrfs_create_new_inode() called for inode X Which properly sets minimal folio order for the VFS inode. - btrfs_update_inode() called for inode X Which calls btrfs_delayed_update_inode() to create a delayed_node into root->delayed_nodes xarray. - Drop cache/memory pressure, evicting in-memory inode X Which evicted the inode X, but delayed_node is still in root->delayed_nodes for future reuse. - btrfs_iget() for inode X called again btrfs_iget() |- btrfs_iget_locked() | |- iget5_locked_rcu() | Which creates a new vfs_inode for btrfs, whose mapping still | has the minimal order as 0. | |- btrfs_read_locked_inode() |- btrfs_fill_inode() | |- btrfs_get_delayed_node() | Which found out the previous node, and use that delayed | node to initialize the new inode. | |- filled = true; |- if (filled) goto cache_index; Which skips the btrfs_update_inode_mapping_flags() and btrfs_set_inode_mapping_order() calls. So the inode still has minimal folio order set as 0, not the required 1. Thus later page cache read will get a folio whose size is smaller than block size, as the mapping has its minimal folio order set as 0 not 1, then trigger the ASSERT(). [FIX] Move the btrfs_update_inode_mapping_flags() and btrfs_set_inode_mapping_order() calls under cache_index label, so that the mapping flags and minimal folio order is always set no matter if we have a cached inode.

CVE 정보

메트릭

메트릭 점수 심각도 CVSS 벡터 출처
V3.1 8.8 HIGH CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/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.

Network

The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).

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 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.

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 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.

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