net/smc: fix UAF in smc_cdc_rx_handler() by pinning the socket

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-64541
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-27 21:17:06 UTC
Updated2026-07-27 21:17:06 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net/smc: fix UAF in smc_cdc_rx_handler() by pinning the socket smc_cdc_rx_handler() looks up the connection by token under the link group's conns_lock, drops the lock, and then dereferences conn and the smc_sock derived from it, ending in sock_hold(&smc->sk) inside smc_cdc_msg_recv(). No reference is held across the lock release. The only reference pinning the socket while the connection is discoverable in the link group is taken in smc_lgr_register_conn() (sock_hold) and dropped in __smc_lgr_unregister_conn() (sock_put), both under conns_lock. Once the handler drops conns_lock, a concurrent close() -> smc_release() -> smc_conn_free() -> smc_lgr_unregister_conn() can drop that reference and free the smc_sock, so the handler's later sock_hold() runs on freed memory: WARNING: lib/refcount.c:25 at refcount_warn_saturate Workqueue: rxe_wq do_work refcount_warn_saturate (lib/refcount.c:25) smc_cdc_msg_recv (net/smc/smc_cdc.c:430) smc_cdc_rx_handler (net/smc/smc_cdc.c:502) smc_wr_rx_tasklet_fn (net/smc/smc_wr.c:445) tasklet_action_common (kernel/softirq.c:938) handle_softirqs (kernel/softirq.c:622) Kernel panic - not syncing: panic_on_warn set Only SMC-R is affected. The SMC-D receive tasklet is stopped by tasklet_kill(&conn->rx_tsklet) in smc_conn_free() before the connection is unregistered, so it cannot run concurrently with the free. Take the socket reference while still holding conns_lock, so the registration reference can no longer be the last one, and drop it once the handler is done.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected d7b0e37c1ac152905b18a5b9506179091a35b0b6 8de4f665d0febfb92803dece377791a563fc7041 git Not specified
CNA Linux Linux affected d7b0e37c1ac152905b18a5b9506179091a35b0b6 8145b432136285e01091815b48ceb2dae261f262 git Not specified
CNA Linux Linux affected d7b0e37c1ac152905b18a5b9506179091a35b0b6 1951bffbc6493ec34cff3956b29d4bc6606904a6 git Not specified
CNA Linux Linux affected d7b0e37c1ac152905b18a5b9506179091a35b0b6 647b19e5cc145a2f1f685ae8ff3805a17356888c git Not specified
CNA Linux Linux affected d7b0e37c1ac152905b18a5b9506179091a35b0b6 472e9d7c0d5b03be3ff91ff941f57da822b031bc git Not specified
CNA Linux Linux affected d7b0e37c1ac152905b18a5b9506179091a35b0b6 3bfb96d9bc6a7ed0b99c7db329cc2e22a28d84bb git Not specified
CNA Linux Linux affected d7b0e37c1ac152905b18a5b9506179091a35b0b6 ce5aa8084329351086894aa34d77e40301d5bd3d git Not specified
CNA Linux Linux affected d7b0e37c1ac152905b18a5b9506179091a35b0b6 9d160b35cc34a2ba8229d07651468a7848325135 git Not specified
CNA Linux Linux affected 4.18 Not specified
CNA Linux Linux unaffected 4.18 semver Not specified
CNA Linux Linux unaffected 5.10.261 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.212 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.178 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.145 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.97 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.40 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.5 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2-rc3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/472e9d7c0d5b03be3ff91ff941f57da822b031bc 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9d160b35cc34a2ba8229d07651468a7848325135 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/647b19e5cc145a2f1f685ae8ff3805a17356888c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3bfb96d9bc6a7ed0b99c7db329cc2e22a28d84bb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/1951bffbc6493ec34cff3956b29d4bc6606904a6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8145b432136285e01091815b48ceb2dae261f262 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ce5aa8084329351086894aa34d77e40301d5bd3d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8de4f665d0febfb92803dece377791a563fc7041 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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