{"cve":"CVE-2024-56640","nvd":{"published":"2024-12-27T15:15:23.730","modified":"2026-08-04T11:22:16.417","status":"Modified","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":["CWE-416"],"references":["https://git.kernel.org/stable/c/0cf598548a6c36d90681d53c6b77d52363f2f295","https://git.kernel.org/stable/c/2c7f14ed9c19ec0f149479d1c2842ec1f9bf76d7","https://git.kernel.org/stable/c/673d606683ac70bc074ca6676b938bff18635226","https://git.kernel.org/stable/c/6f0ae06a234a78ae137064f2c89135ac078a00eb","https://git.kernel.org/stable/c/f502a88fdd415647a1f2dc45fac71b9c522a052b"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:57:56.913276502+00:00"},"epss":{"cve":"CVE-2024-56640","score":0.00618,"percentile":0.49652,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}