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CVE-2026-80980
net/smc: stop killed, freed and out_of_sync sharing a byte
Published 2026-09-11 (37 days ago) by the Linux kernel CNA. Subsystem net/smc. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-80980 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | fixedDSA-6568-1 · 2026-10-16 · text | 6.12.113-1 | Update the kernel and reboot. DSA-6568-1 shipped the fix on 2026-10-16, in 6.12.113-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The three connection state flags are single-bit bitfields, so they occupy one byte of struct smc_connection and every store to one is a read-modify-write of the other two: u8 killed : 1; u8 freed : 1; u8 out_of_sync : 1; They are not written under a common lock. smc_cdc_msg_validate() sets out_of_sync from the receive tasklet, while smc_conn_kill() sets killed from process context under lock_sock(), and the receive path does not defer to the backlog when the socket is owned -- smc_cdc_msg_recv() takes only bh_lock_sock(). Give each flag its own byte so a store no longer touches its neighbours. All readers test them as booleans and are unchanged. struct smc_connection grows by two bytes.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
net/smc/smc.h
- What this is
- SHARED MEMORY COMMUNICATIONS (SMC) SOCKETSMAINTAINERS section matched on net/smc/ · linux-rdma@vger.kernel.org · Supported
Show whether Debian builds this, per release
Not established. This site could not find the build rule for the affected file in the kernel trees Debian ships, so it has no answer about whether Debian compiles this code. Read that as unknown, never as absent.
- bookworm, trixie, forky, sid?
- ?
- not established - no Makefile entry for the affected file
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS
Signals
- Published
- 2026-09-11 (37 days ago)source
- CVSS
- 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.67%, higher than 51.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/smc
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.8 | 6.12.112 | 09a9cbadc05f |
| 5.8 | 6.18.50 | 313f79149eb3 |
| 5.8 | 7.2.4 | 2cb7a8d64b7e |
| 5.8 | 7.3 | db51a8658c11 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DSA-6568-1 | 2026-10-16 | trixie 6.12.113-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- smc_cdc_msg_validate() runs from the SMC-R CDC receive tasklet on RDMA completions, and teardown is driven by CLC DECLINE (FIRST_CONTACT) or LLC DELETE_LINK_ALL from the same peer. SMC-Rv2 is RoCEv2 over UDP/4791 (IP-routable) with the CLC handshake on plain TCP, so a remote host that can reach an AF_SMC listener hits the path.
- AC:LAttack complexity, low
- The attacker controls both sides of the race: it sends CDC failover_validation messages that store out_of_sync from the receive tasklet (no sock lock) while concurrently forcing smc_conn_kill()/smc_conn_free() via CLC decline, CDC close/abort, or LLC link-delete, and can retry across many connections in the same link group.
- PR:NPrivileges required, none
- SMC has no peer authentication. Completing the CLC handshake to a listening AF_SMC/IPPROTO_SMC socket and sending CDC/CLC/LLC messages requires no credentials, capabilities, or local account, matching other SMC remote bugs.
- UI:NUser interaction, none
- CDC is processed in a softirq tasklet from the RDMA completion queue and CLC decline is handled in the handshake worker; no local user or application action is required beyond the already-listening SMC server.
- S:UScope, unchanged
- The corrupted flags and resulting UAF stay inside kernel objects (smc_connection, smc_sock, smc_link_group) in the same security authority; no VM, IOMMU, or sandbox boundary is crossed.
- C:HConfidentiality impact, high
- A lost killed/freed/out_of_sync bit from the shared-byte RMW lets CDC continue after unregister or lets smc_conn_free() run twice (duplicate smc_lgr_put), a use-after-free of the socket and link group that can be reallocated to disclose kernel memory.
- I:HIntegrity impact, high
- The same UAF/double-free writes through a reused smc_sock (sk_err, sk_data_ready, queue_work on abort_work/close_work) and link-group refcounts, giving heap-spray primitives for arbitrary kernel write and control-flow hijack.
- A:HAvailability impact, high
- Use-after-free and double-free of the connection and link group oops or panic in softirq/workqueue context (refcount underflow, as in related SMC UAFs), and the attacker can trigger it repeatedly without authentication.