{"id":"CVE-2024-56640","summary":"net/smc: fix LGR and link use-after-free issue","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/smc: fix LGR and link use-after-free issue\n\nWe encountered a LGR/link use-after-free issue, which manifested as\nthe LGR/link refcnt reaching 0 early and entering the clear process,\nmaking resource access unsafe.\n\n refcount_t: addition on 0; use-after-free.\n WARNING: CPU: 14 PID: 107447 at lib/refcount.c:25 refcount_warn_saturate+0x9c/0x140\n Workqueue: events smc_lgr_terminate_work [smc]\n Call trace:\n  refcount_warn_saturate+0x9c/0x140\n  __smc_lgr_terminate.part.45+0x2a8/0x370 [smc]\n  smc_lgr_terminate_work+0x28/0x30 [smc]\n  process_one_work+0x1b8/0x420\n  worker_thread+0x158/0x510\n  kthread+0x114/0x118\n\nor\n\n refcount_t: underflow; use-after-free.\n WARNING: CPU: 6 PID: 93140 at lib/refcount.c:28 refcount_warn_saturate+0xf0/0x140\n Workqueue: smc_hs_wq smc_listen_work [smc]\n Call trace:\n  refcount_warn_saturate+0xf0/0x140\n  smcr_link_put+0x1cc/0x1d8 [smc]\n  smc_conn_free+0x110/0x1b0 [smc]\n  smc_conn_abort+0x50/0x60 [smc]\n  smc_listen_find_device+0x75c/0x790 [smc]\n  smc_listen_work+0x368/0x8a0 [smc]\n  process_one_work+0x1b8/0x420\n  worker_thread+0x158/0x510\n  kthread+0x114/0x118\n\nIt is caused by repeated release of LGR/link refcnt. One suspect is that\nsmc_conn_free() is called repeatedly because some smc_conn_free() from\nserver listening path are not protected by sock lock.\n\ne.g.\n\nCalls under socklock        | smc_listen_work\n-------------------------------------------------------\nlock_sock(sk)               | smc_conn_abort\nsmc_conn_free               | \\- smc_conn_free\n\\- smcr_link_put            |    \\- smcr_link_put (duplicated)\nrelease_sock(sk)\n\nSo here add sock lock protection in smc_listen_work() path, making it\nexclusive with other connection operations.","modified":"2026-03-20T12:40:55.632822Z","published":"2024-12-27T15:02:42.253Z","related":["MGASA-2025-0030","MGASA-2025-0032","SUSE-SU-2025:01919-1","SUSE-SU-2025:01951-1","SUSE-SU-2025:01967-1","SUSE-SU-2025:1177-1","SUSE-SU-2025:1178-1","SUSE-SU-2025:1180-1","SUSE-SU-2025:1293-1","SUSE-SU-2025:20190-1","SUSE-SU-2025:20192-1","SUSE-SU-2025:20260-1","SUSE-SU-2025:20270-1","USN-7379-2","USN-7380-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/56xxx/CVE-2024-56640.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0cf598548a6c36d90681d53c6b77d52363f2f295"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2c7f14ed9c19ec0f149479d1c2842ec1f9bf76d7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/673d606683ac70bc074ca6676b938bff18635226"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6f0ae06a234a78ae137064f2c89135ac078a00eb"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f502a88fdd415647a1f2dc45fac71b9c522a052b"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/56xxx/CVE-2024-56640.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-56640"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8"},{"fixed":"f502a88fdd415647a1f2dc45fac71b9c522a052b"},{"fixed":"0cf598548a6c36d90681d53c6b77d52363f2f295"},{"fixed":"673d606683ac70bc074ca6676b938bff18635226"},{"fixed":"6f0ae06a234a78ae137064f2c89135ac078a00eb"},{"fixed":"2c7f14ed9c19ec0f149479d1c2842ec1f9bf76d7"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2024-56640.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}