protocol is htons(ETH_P_802_2), otherwise, __llc_lookup_established() and __llc_lookup_listener() will read garbage. The missing initialisation existed prior to commit 211ed865108e ("net: delete all instances of special processing for token ring"). It removed the part to kick out the token ring stuff but forgot to close the door allowing ETH_P_TR_802_2 packets to sneak into llc_rcv(). Let's remove llc_tr_packet_type and complete the deprecation. [0]: BUG: KMSAN: uninit-value in __llc_lookup_established+0xe9d/0xf90 __llc_lookup_established+0xe9d/0xf90 __llc_lookup net/llc/llc_conn.c:611 [inline] llc_conn_handler+0x4bd/0x1360 net/llc/llc_conn.c:791 llc_rcv+0xfbb/0x14a0 net/llc/llc_input.c:206 __netif_receive_skb_one_core net/core/dev.c:5527 [inline] __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5641 netif_receive_skb_internal net/core/dev.c:5727 [inline] netif_receive_skb+0x58/0x660 net/core/dev.c:5786 tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1555 tun_get_user+0x53af/0x66d0 drivers/net/tun.c:2002 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048 call_write_iter include/linux/fs.h:2020 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x8ef/0x1490 fs/read_write.c:584 ksys_write+0x20f/0x4c0 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __x64_sys_write+0x93/0xd0 fs/read_write.c:646 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b Local variable daddr created at: llc_conn_handler+0x53/0x1360 net/llc/llc_conn.c:783 llc_rcv+0xfbb/0x14a0 net/llc/llc_input.c:206 CPU: 1 PID: 5004 Comm: syz-executor994 Not tainted 6.6.0-syzkaller-14500-g1c41041124bd #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023">

CVE-2024-26635 : Detail

CVE-2024-26635

5.5
/
Medium
0.04%V3
Local
2024-03-18
10h14 +00:00
2024-12-19
08h43 +00:00
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CVE Descriptions

llc: Drop support for ETH_P_TR_802_2.

In the Linux kernel, the following vulnerability has been resolved: llc: Drop support for ETH_P_TR_802_2. syzbot reported an uninit-value bug below. [0] llc supports ETH_P_802_2 (0x0004) and used to support ETH_P_TR_802_2 (0x0011), and syzbot abused the latter to trigger the bug. write$tun(r0, &(0x7f0000000040)={@val={0x0, 0x11}, @val, @mpls={[], @llc={@snap={0xaa, 0x1, ')', "90e5dd"}}}}, 0x16) llc_conn_handler() initialises local variables {saddr,daddr}.mac based on skb in llc_pdu_decode_sa()/llc_pdu_decode_da() and passes them to __llc_lookup(). However, the initialisation is done only when skb->protocol is htons(ETH_P_802_2), otherwise, __llc_lookup_established() and __llc_lookup_listener() will read garbage. The missing initialisation existed prior to commit 211ed865108e ("net: delete all instances of special processing for token ring"). It removed the part to kick out the token ring stuff but forgot to close the door allowing ETH_P_TR_802_2 packets to sneak into llc_rcv(). Let's remove llc_tr_packet_type and complete the deprecation. [0]: BUG: KMSAN: uninit-value in __llc_lookup_established+0xe9d/0xf90 __llc_lookup_established+0xe9d/0xf90 __llc_lookup net/llc/llc_conn.c:611 [inline] llc_conn_handler+0x4bd/0x1360 net/llc/llc_conn.c:791 llc_rcv+0xfbb/0x14a0 net/llc/llc_input.c:206 __netif_receive_skb_one_core net/core/dev.c:5527 [inline] __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5641 netif_receive_skb_internal net/core/dev.c:5727 [inline] netif_receive_skb+0x58/0x660 net/core/dev.c:5786 tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1555 tun_get_user+0x53af/0x66d0 drivers/net/tun.c:2002 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048 call_write_iter include/linux/fs.h:2020 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x8ef/0x1490 fs/read_write.c:584 ksys_write+0x20f/0x4c0 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __x64_sys_write+0x93/0xd0 fs/read_write.c:646 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b Local variable daddr created at: llc_conn_handler+0x53/0x1360 net/llc/llc_conn.c:783 llc_rcv+0xfbb/0x14a0 net/llc/llc_input.c:206 CPU: 1 PID: 5004 Comm: syz-executor994 Not tainted 6.6.0-syzkaller-14500-g1c41041124bd #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-909 Missing Initialization of Resource
The product does not initialize a critical resource.

Metrics

Metrics Score Severity CVSS Vector Source
V3.1 5.5 MEDIUM CVSS:3.1/AV:L/AC:L/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.

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.

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.

[email protected]

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) 3.5 To (excluding) 4.19.307

Linux>>Linux_kernel >> Version From (including) 4.20 To (excluding) 5.4.269

Linux>>Linux_kernel >> Version From (including) 5.5 To (excluding) 5.10.210

Linux>>Linux_kernel >> Version From (including) 5.11 To (excluding) 5.15.149

Linux>>Linux_kernel >> Version From (including) 5.16 To (excluding) 6.1.76

Linux>>Linux_kernel >> Version From (including) 6.2 To (excluding) 6.6.15

Linux>>Linux_kernel >> Version From (including) 6.7 To (excluding) 6.7.3

Linux>>Linux_kernel >> Version 6.8

Configuraton 0

Debian>>Debian_linux >> Version 10.0

References