CVE-2024-56640net/smc: fix LGR and link use-after-free issue
- 9.8CriticalCVSS base score
- 0.62%Exploitation in 30 daysEPSS · top 50% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By Linux
Published
- 20 months later
· 20 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| CISA-ADPADP (enrichment) | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Modified | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.62% · top 50% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.8.
Affected products
- affected 3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 – < f502a88fdd415647a1f2dc45fac71b9c522a052b
- affected 3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 – < 0cf598548a6c36d90681d53c6b77d52363f2f295
- affected 3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 – < 673d606683ac70bc074ca6676b938bff18635226
- affected 3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 – < 6f0ae06a234a78ae137064f2c89135ac078a00eb
- affected 3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 – < 2c7f14ed9c19ec0f149479d1c2842ec1f9bf76d7
- affected 4.18
- unaffected < 4.18
- unaffected 5.15.174 – ≤ 5.15.*
- unaffected 6.1.120 – ≤ 6.1.*
- unaffected 6.6.66 – ≤ 6.6.*
- unaffected 6.12.5 – ≤ 6.12.*
- unaffected 6.13 – ≤ *
References
References6
- https://git.kernel.org/stable/c/f502a88fdd415647a1f2dc45fac71b9c522a052b (opens in a new tab)
- https://git.kernel.org/stable/c/0cf598548a6c36d90681d53c6b77d52363f2f295 (opens in a new tab)
- https://git.kernel.org/stable/c/673d606683ac70bc074ca6676b938bff18635226 (opens in a new tab)
- https://git.kernel.org/stable/c/6f0ae06a234a78ae137064f2c89135ac078a00eb (opens in a new tab)
- https://git.kernel.org/stable/c/2c7f14ed9c19ec0f149479d1c2842ec1f9bf76d7 (opens in a new tab)
- https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2024-53288 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2024-56640)Record last updated .