{"id":"CVE-2026-64541","summary":"net/smc: fix UAF in smc_cdc_rx_handler() by pinning the socket","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/smc: fix UAF in smc_cdc_rx_handler() by pinning the socket\n\nsmc_cdc_rx_handler() looks up the connection by token under the link\ngroup's conns_lock, drops the lock, and then dereferences conn and the\nsmc_sock derived from it, ending in sock_hold(&smc-\u003esk) inside\nsmc_cdc_msg_recv(). No reference is held across the lock release.\n\nThe only reference pinning the socket while the connection is\ndiscoverable in the link group is taken in smc_lgr_register_conn()\n(sock_hold) and dropped in __smc_lgr_unregister_conn() (sock_put), both\nunder conns_lock. Once the handler drops conns_lock, a concurrent\nclose() -\u003e smc_release() -\u003e smc_conn_free() -\u003e smc_lgr_unregister_conn()\ncan drop that reference and free the smc_sock, so the handler's later\nsock_hold() runs on freed memory:\n\n  WARNING: lib/refcount.c:25 at refcount_warn_saturate\n  Workqueue: rxe_wq do_work\n   refcount_warn_saturate (lib/refcount.c:25)\n   smc_cdc_msg_recv (net/smc/smc_cdc.c:430)\n   smc_cdc_rx_handler (net/smc/smc_cdc.c:502)\n   smc_wr_rx_tasklet_fn (net/smc/smc_wr.c:445)\n   tasklet_action_common (kernel/softirq.c:938)\n   handle_softirqs (kernel/softirq.c:622)\n  Kernel panic - not syncing: panic_on_warn set\n\nOnly SMC-R is affected. The SMC-D receive tasklet is stopped by\ntasklet_kill(&conn-\u003erx_tsklet) in smc_conn_free() before the connection\nis unregistered, so it cannot run concurrently with the free.\n\nTake the socket reference while still holding conns_lock, so the\nregistration reference can no longer be the last one, and drop it once\nthe handler is done.","modified":"2026-07-28T04:02:28.178818826Z","published":"2026-07-27T20:10:34.439Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64541.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1951bffbc6493ec34cff3956b29d4bc6606904a6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3bfb96d9bc6a7ed0b99c7db329cc2e22a28d84bb"},{"type":"WEB","url":"https://git.kernel.org/stable/c/472e9d7c0d5b03be3ff91ff941f57da822b031bc"},{"type":"WEB","url":"https://git.kernel.org/stable/c/647b19e5cc145a2f1f685ae8ff3805a17356888c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8145b432136285e01091815b48ceb2dae261f262"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8de4f665d0febfb92803dece377791a563fc7041"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9d160b35cc34a2ba8229d07651468a7848325135"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ce5aa8084329351086894aa34d77e40301d5bd3d"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64541.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64541"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"d7b0e37c1ac152905b18a5b9506179091a35b0b6"},{"fixed":"8de4f665d0febfb92803dece377791a563fc7041"},{"fixed":"8145b432136285e01091815b48ceb2dae261f262"},{"fixed":"1951bffbc6493ec34cff3956b29d4bc6606904a6"},{"fixed":"647b19e5cc145a2f1f685ae8ff3805a17356888c"},{"fixed":"472e9d7c0d5b03be3ff91ff941f57da822b031bc"},{"fixed":"3bfb96d9bc6a7ed0b99c7db329cc2e22a28d84bb"},{"fixed":"ce5aa8084329351086894aa34d77e40301d5bd3d"},{"fixed":"9d160b35cc34a2ba8229d07651468a7848325135"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64541.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.18.0"},{"fixed":"5.10.261"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.212"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.178"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.97"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.40"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64541.json"}}],"schema_version":"1.7.5"}