CVE-2024-35982

medium

Description

In the Linux kernel, the following vulnerability has been resolved: batman-adv: Avoid infinite loop trying to resize local TT If the MTU of one of an attached interface becomes too small to transmit the local translation table then it must be resized to fit inside all fragments (when enabled) or a single packet. But if the MTU becomes too low to transmit even the header + the VLAN specific part then the resizing of the local TT will never succeed. This can for example happen when the usable space is 110 bytes and 11 VLANs are on top of batman-adv. In this case, at least 116 byte would be needed. There will just be an endless spam of batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (110) in the log but the function will never finish. Problem here is that the timeout will be halved all the time and will then stagnate at 0 and therefore never be able to reduce the table even more. There are other scenarios possible with a similar result. The number of BATADV_TT_CLIENT_NOPURGE entries in the local TT can for example be too high to fit inside a packet. Such a scenario can therefore happen also with only a single VLAN + 7 non-purgable addresses - requiring at least 120 bytes. While this should be handled proactively when: * interface with too low MTU is added * VLAN is added * non-purgeable local mac is added * MTU of an attached interface is reduced * fragmentation setting gets disabled (which most likely requires dropping attached interfaces) not all of these scenarios can be prevented because batman-adv is only consuming events without the the possibility to prevent these actions (non-purgable MAC address added, MTU of an attached interface is reduced). It is therefore necessary to also make sure that the code is able to handle also the situations when there were already incompatible system configuration are present.

References

https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html

https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html

https://git.kernel.org/stable/c/ca54e2671548616ad34885f90d4f26f7adb088f0

https://git.kernel.org/stable/c/b3ddf6904073990492454b1dd1c10a24be8c74c6

https://git.kernel.org/stable/c/b1f532a3b1e6d2e5559c7ace49322922637a28aa

https://git.kernel.org/stable/c/87b6af1a7683e021710c08fc0551fc078346032f

https://git.kernel.org/stable/c/70a8be9dc2fb65d67f8c1e0c88c587e08e2e575d

https://git.kernel.org/stable/c/4ca2a5fb54ea2cc43edea614207fcede562d91c2

https://git.kernel.org/stable/c/3fe79b2c83461edbbf86ed8a6f3924820ff89259

https://git.kernel.org/stable/c/04720ea2e6c64459a90ca28570ea78335eccd924

Details

Source: Mitre, NVD

Published: 2024-05-20

Updated: 2024-07-03

Risk Information

CVSS v2

Base Score: 4.6

Vector: CVSS2#AV:L/AC:L/Au:S/C:N/I:N/A:C

Severity: Medium

CVSS v3

Base Score: 5.5

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Severity: Medium