CVE-2026-80983

What the bug is

smc_switch_conns() takes a reference on the SMC socket before dropping lgr->conns_lock, so the connection stays alive while the CDC slot is fetched: sock_hold(&smc->sk); read_unlock_bh(&lgr->conns_lock); /* pre-fetch buffer outside of send_lock, might sleep */ rc = smc_cdc_get_free_slot(conn, to_lnk, &wr_buf, NULL, &pend); if (rc) goto err_out; The err_out label only drops the wr_tx link reference, so this early exit returns without the matching sock_put(). The second error exit is not affected, because sock_put() has already run by then. A leaked sk_refcnt means the smc_sock is never destroyed. Its send and receive buffers stay allocated, and for a user socket the reference held on the network namespace is never released, so the netns can no longer be torn down. smc_cdc_get_free_slot() fails when the target link goes down or when the connection has been killed while the switch is in progress. Both are reachable during the link failover this function implements, so the leak is triggered by the same hardware events that make smc_switch_conns() run in the first place. Restructure so there is a single sock_put() covering both outcomes, instead of adding a second one to the error path.

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_core.c

What this is

SHARED MEMORY COMMUNICATIONS (SMC) SOCKETSMAINTAINERS section matched on net/smc/ · linux-rdma@vger.kernel.org · Supported

Kernel module

smc

Check it on the machine

grep -w CONFIG_SMC /boot/config-$(uname -r)

Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.

lsmod | grep -w smc

Prints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.

Show whether Debian builds this, per release

Debian does not build this code in 2 releases. It does build it in 3 releases, so the answer depends on which release the machine runs.

• bookworm, trixiem
• forky, sidn
• bookworm · linux-6.12m

m

a loadable module on every flavour - check lsmod, can be blacklisted

n

not enabled on any flavour - this release does not build the code

Build switch

CONFIG_SMC

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 kbuild Makefiles Debian linux-config packages

Signals

Published

2026-09-11 (37 days ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.17%, higher than 6.2% 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
5.15	5.15.221	a3378466704e
5.15	6.1.188	e20227019d9d
5.15	6.6.157	09d7a9e162ee
5.15	6.12.109	84dea0585f6b
5.15	6.18.50	d89dc1bd8845
5.15	7.2.4	d9a879ac2595
5.15	7.3	719296c4aa82
5.10.90	0	0
5.14.14	0	0

Debian advisories