CVE-2024-45009: mptcp: pm: only decrement add_addr_accepted for MPJ req

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-09-11 · updated 2026-08-04

Description

In the Linux kernel, the following vulnerability has been resolved: mptcp: pm: only decrement add_addr_accepted for MPJ req Adding the following warning ... WARN_ON_ONCE(msk->pm.add_addr_accepted == 0) ... before decrementing the add_addr_accepted counter helped to find a bug when running the "remove single subflow" subtest from the mptcp_join.sh selftest. Removing a 'subflow' endpoint will first trigger a RM_ADDR, then the subflow closure. Before this patch, and upon the reception of the RM_ADDR, the other peer will then try to decrement this add_addr_accepted. That's not correct because the attached subflows have not been created upon the reception of an ADD_ADDR. A way to solve that is to decrement the counter only if the attached subflow was an MP_JOIN to a remote id that was not 0, and initiated by the host receiving the RM_ADDR.

Affected products

Linux kernel: from 5.10 before 5.15.167; from 5.16 before 6.1.107; from 6.2 before 6.6.48; from 6.7 before 6.10.7; 6.11-rc1, 6.11-rc2, 6.11-rc3, 6.11-rc4 — fixed in 5.15.167, 6.1.107, 6.10.7, 6.6.48

How to fix

Upgrade to a fixed version: Linux kernel 5.15.167, 6.1.107, 6.10.7, 6.6.48. Check the vendor advisory for mitigations.

References

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