{"id":"DEBIAN-CVE-2024-56640","details":"In the Linux kernel, the following vulnerability has been resolved:  net/smc: fix LGR and link use-after-free issue  We encountered a LGR/link use-after-free issue, which manifested as the LGR/link refcnt reaching 0 early and entering the clear process, making resource access unsafe.   refcount_t: addition on 0; use-after-free.  WARNING: CPU: 14 PID: 107447 at lib/refcount.c:25 refcount_warn_saturate+0x9c/0x140  Workqueue: events smc_lgr_terminate_work [smc]  Call trace:   refcount_warn_saturate+0x9c/0x140   __smc_lgr_terminate.part.45+0x2a8/0x370 [smc]   smc_lgr_terminate_work+0x28/0x30 [smc]   process_one_work+0x1b8/0x420   worker_thread+0x158/0x510   kthread+0x114/0x118  or   refcount_t: underflow; use-after-free.  WARNING: CPU: 6 PID: 93140 at lib/refcount.c:28 refcount_warn_saturate+0xf0/0x140  Workqueue: smc_hs_wq smc_listen_work [smc]  Call trace:   refcount_warn_saturate+0xf0/0x140   smcr_link_put+0x1cc/0x1d8 [smc]   smc_conn_free+0x110/0x1b0 [smc]   smc_conn_abort+0x50/0x60 [smc]   smc_listen_find_device+0x75c/0x790 [smc]   smc_listen_work+0x368/0x8a0 [smc]   process_one_work+0x1b8/0x420   worker_thread+0x158/0x510   kthread+0x114/0x118  It is caused by repeated release of LGR/link refcnt. One suspect is that smc_conn_free() is called repeatedly because some smc_conn_free() from server listening path are not protected by sock lock.  e.g.  Calls under socklock        | smc_listen_work ------------------------------------------------------- lock_sock(sk)               | smc_conn_abort smc_conn_free               | \\- smc_conn_free \\- smcr_link_put            |    \\- smcr_link_put (duplicated) release_sock(sk)  So here add sock lock protection in smc_listen_work() path, making it exclusive with other connection operations.","modified":"2026-09-15T09:03:00.129741320Z","published":"2024-12-27T15:15:23.730Z","upstream":["CVE-2024-56640"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2024-56640"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.123-1"}]}],"versions":["6.1.106-1","6.1.106-2","6.1.106-3","6.1.112-1","6.1.115-1","6.1.119-1","6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2024-56640.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.5-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2024-56640.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.5-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2024-56640.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}