CVE-2026-23118: rxrpc: Fix data-race warning and potential load/store tearing
In the Linux kernel, the following vulnerability has been resolved:
rxrpc: Fix data-race warning and potential load/store tearing
Fix the following:
BUG: KCSAN: data-race in rxrpcpeerkeepaliveworker / rxrpcsenddatapacket
which is reporting an issue with the reads and writes to ->lasttxat in:
conn->peer->lasttxat = ktimegetseconds();
and:
keepaliveat = peer->lasttxat + RXRPCKEEPALIVETIME;
The lockless accesses to these to values aren't actually a problem as the read only needs an approximate time of last transmission for the purposes of deciding whether or not the transmission of a keepalive packet is warranted yet.
Also, as ->lasttxat is a 64-bit value, tearing can occur on a 32-bit arch.
Fix both of these by switching to an unsigned int for ->lasttxat and only storing the LSW of the time64t. It can then be reconstructed at need provided no more than 68 years has elapsed since the last transmission.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1064.72+fips1 - Compensating control
In the Linux kernel rxrpc implementation, change ->last_tx_at from a 64-bit value to unsigned int and store only the least-significant word (LSW) of the time64_t, reconstructing it when needed.
Event History
Frequently Asked Questions
What level of access and effort does exploitation require?
The CVSS vector indicates local access, low privileges, and high attack complexity are required. No user interaction is required.
What is the primary security impact?
The reported impact is availability only, rated High in the CVSS vector. The vector reports no confidentiality or integrity impact.
Are 32-bit systems subject to an additional risk?
Yes. The vulnerable 64-bit last-transmission timestamp can be torn when read or written on 32-bit architectures. The fix stores an unsigned-int low-order timestamp value to avoid this.
How might this issue appear during testing or monitoring?
The issue was reported as a KCSAN data-race warning involving rxrpc_peer_keepalive_worker and rxrpc_send_data_packet, with concurrent accesses to peer->last_tx_at.