CVE-2024-26826

Summary

In the Linux kernel, the following vulnerability has been resolved:

mptcp: fix data re-injection from stale subflow

When the MPTCP PM detects that a subflow is stale, all the packet scheduler must re-inject all the mptcp-level unacked data. To avoid acquiring unneeded locks, it first try to check if any unacked data is present at all in the RTX queue, but such check is currently broken, as it uses TCP-specific helper on an MPTCP socket.

Funnily enough fuzzers and static checkers are happy, as the accessed memory still belongs to the mptcp_sock struct, and even from a functional perspective the recovery completed successfully, as the short-cut test always failed.

A recent unrelated TCP change - commit d5fed5addb2b ("tcp: reorganize tcp_sock fast path variables") - exposed the issue, as the tcp field reorganization makes the mptcp code always skip the re-inection.

Fix the issue dropping the bogus call: we are on a slow path, the early optimization proved once again to be evil.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux1e1d9d6f119c55c05e8ea78ed3e49046690abffd < 6f95120f898b40d13fd441225ef511307853c9c2affected
LinuxLinux1e1d9d6f119c55c05e8ea78ed3e49046690abffd < 6673d9f1c2cd984390550dbdf7d5ae07b20abbf8affected
LinuxLinux1e1d9d6f119c55c05e8ea78ed3e49046690abffd < b609c783c535493aa3fca22c7e40a120370b1ca5affected
LinuxLinux1e1d9d6f119c55c05e8ea78ed3e49046690abffd < 624902eab7abcb8731b333ec73f206d38d839cd8affected
LinuxLinux1e1d9d6f119c55c05e8ea78ed3e49046690abffd < b6c620dc43ccb4e802894e54b651cf81495e9598affected
LinuxLinux5.15affected
LinuxLinux0 < 5.15unaffected
LinuxLinux5.15.149 <= 5.15.*unaffected
LinuxLinux6.1.79 <= 6.1.*unaffected
LinuxLinux6.6.18 <= 6.6.*unaffected
LinuxLinux6.7.6 <= 6.7.*unaffected
LinuxLinux6.8 <= *unaffected

Weaknesses

ADP Enrichment

CVE Program Container

Additional References

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References