CVE-2024-56640

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2024-56640", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-27T15:00:39.839Z", "datePublished": "2024-12-27T15:02:42.253Z", "dateUpdated": "2026-08-05T11:45:38.986Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:45:38.986Z"}, "descriptions": [{"lang": "en", "value": "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."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL"}, "scenarios": [{"lang": "en", "value": "AV:N - The bug is in `smc_listen_work()`, the SMC server-side CLC handshake worker that is queued from `smc_tcp_listen_work()` for every inbound TCP connection carrying the SMC option, and it processes CLC Proposal/Confirm/Decline messages sent by the remote peer over routable TCP/IP. A remote host that can reach an AF_SMC listener drives the entire vulnerable path.\nAC:L - The attacker controls both sides of the race: `smc_clc_wait_msg()` (net/smc/smc_clc.c:784-794) accepts a CLC DECLINE at any point, and with the attacker-chosen `SMC_FIRST_CONTACT_MASK` bit set it calls `smc_lgr_terminate_sched()`, scheduling `__smc_lgr_terminate()` (which takes lock_sock and frees conn state) concurrently with the unlocked `smc_listen_work()` \u2192 `smc_conn_abort()` \u2192 `smc_conn_free()` path, whose `conn->freed` guard is an unsynchronized bitfield. The attacker can open unlimited parallel connections into the same link group on the separate `smc_hs_wq` and retry indefinitely at no cost.\nPR:N - The CLC handshake in `smc_listen_work()` runs entirely before any application-level authentication and requires no credentials \u2014 the attacker only needs to complete a TCP connection to the SMC listener. No capability, namespace, or local account is involved.\nUI:N - The listen worker is queued automatically from the TCP accept path by `smc_clcsock_data_ready()`/`smc_tcp_listen_work()`; no action by the local user or administrator is needed beyond running the SMC server that is already listening.\nS:U - The corruption is confined to kernel heap objects (`struct smc_link_group`, `struct smc_link`) within the same kernel security authority, with no crossing of a VM, IOMMU, or sandbox boundary.\nC:H - The duplicate `smcr_link_put()`/`smc_lgr_put()` drives the refcounts to zero early, so the `kzalloc`'d `struct smc_link_group` is `kfree()`d while `__smc_lgr_terminate()`, `smc_listen_work()`, and the LLC/CDC paths still dereference it \u2014 a classic use-after-free read of a generic kmalloc slab object that an attacker can reallocate and shape, leaking link-group state including `peer_systemid` and RDMA `rtokens` (remote keys/addresses).\nI:H - Post-free writes into the reallocated object include `lgr->sync_err`/`terminating` bitfields, `refcount_inc()`, and list/rb-tree manipulation, while the freed structure embeds `struct work_struct terminate_work`, `struct delayed_work free_work`, and per-link `link_down_wrk` \u2014 function pointers that `schedule_work()`/`smc_lgr_schedule_free_work()` will subsequently invoke, giving a heap-spray path to control-flow hijack.\nA:H - The commit documents real production `refcount_t: underflow`/`addition on 0` warnings in `smcr_link_put()` and `__smc_lgr_terminate()`; refcount saturation plus use of freed link-group memory yields oopses and kernel panics, and the condition is remotely and repeatably triggerable."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/smc/af_smc.c"], "versions": [{"version": "3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8", "lessThan": "f502a88fdd415647a1f2dc45fac71b9c522a052b", "status": "affected", "versionType": "git"}, {"version": "3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8", "lessThan": "0cf598548a6c36d90681d53c6b77d52363f2f295", "status": "affected", "versionType": "git"}, {"version": "3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8", "lessThan": "673d606683ac70bc074ca6676b938bff18635226", "status": "affected", "versionType": "git"}, {"version": "3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8", "lessThan": "6f0ae06a234a78ae137064f2c89135ac078a00eb", "status": "affected", "versionType": "git"}, {"version": "3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8", "lessThan": "2c7f14ed9c19ec0f149479d1c2842ec1f9bf76d7", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/smc/af_smc.c"], "versions": [{"version": "4.18", "status": "affected"}, {"version": "0", "lessThan": "4.18", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.174", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.120", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.66", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.5", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.13", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "5.15.174"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "6.1.120"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "6.6.66"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "6.12.5"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "6.13"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/f502a88fdd415647a1f2dc45fac71b9c522a052b"}, {"url": "https://git.kernel.org/stable/c/0cf598548a6c36d90681d53c6b77d52363f2f295"}, {"url": "https://git.kernel.org/stable/c/673d606683ac70bc074ca6676b938bff18635226"}, {"url": "https://git.kernel.org/stable/c/6f0ae06a234a78ae137064f2c89135ac078a00eb"}, {"url": "https://git.kernel.org/stable/c/2c7f14ed9c19ec0f149479d1c2842ec1f9bf76d7"}], "title": "net/smc: fix LGR and link use-after-free issue", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH"}}, {"other": {"type": "ssvc", "content": {"id": "CVE-2024-56640", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2025-02-11T15:41:51.231757Z"}}}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-416", "description": "CWE-416 Use After Free"}]}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-02-11T15:45:22.074Z"}}, {"title": "CVE Program Container", "references": [{"url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html"}], "providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T20:51:40.000Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CVE Program Container", "references": [{"url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html"}], "providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T20:51:40.000Z"}}, {"title": "CISA ADP Vulnrichment", "metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH"}}, {"other": {"type": "ssvc", "content": {"id": "CVE-2024-56640", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2025-02-11T15:41:51.231757Z"}}}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-416", "description": "CWE-416 Use After Free"}]}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-02-11T15:41:52.600Z"}}], "cna": {"title": "net/smc: fix LGR and link use-after-free issue", "metrics": [{"cvssV3_1": {"version": "3.1", "baseScore": 9.8, "baseSeverity": "CRITICAL", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}, "scenarios": [{"lang": "en", "value": "AV:N - The bug is in `smc_listen_work()`, the SMC server-side CLC handshake worker that is queued from `smc_tcp_listen_work()` for every inbound TCP connection carrying the SMC option, and it processes CLC Proposal/Confirm/Decline messages sent by the remote peer over routable TCP/IP. A remote host that can reach an AF_SMC listener drives the entire vulnerable path.\nAC:L - The attacker controls both sides of the race: `smc_clc_wait_msg()` (net/smc/smc_clc.c:784-794) accepts a CLC DECLINE at any point, and with the attacker-chosen `SMC_FIRST_CONTACT_MASK` bit set it calls `smc_lgr_terminate_sched()`, scheduling `__smc_lgr_terminate()` (which takes lock_sock and frees conn state) concurrently with the unlocked `smc_listen_work()` \u2192 `smc_conn_abort()` \u2192 `smc_conn_free()` path, whose `conn->freed` guard is an unsynchronized bitfield. The attacker can open unlimited parallel connections into the same link group on the separate `smc_hs_wq` and retry indefinitely at no cost.\nPR:N - The CLC handshake in `smc_listen_work()` runs entirely before any application-level authentication and requires no credentials \u2014 the attacker only needs to complete a TCP connection to the SMC listener. No capability, namespace, or local account is involved.\nUI:N - The listen worker is queued automatically from the TCP accept path by `smc_clcsock_data_ready()`/`smc_tcp_listen_work()`; no action by the local user or administrator is needed beyond running the SMC server that is already listening.\nS:U - The corruption is confined to kernel heap objects (`struct smc_link_group`, `struct smc_link`) within the same kernel security authority, with no crossing of a VM, IOMMU, or sandbox boundary.\nC:H - The duplicate `smcr_link_put()`/`smc_lgr_put()` drives the refcounts to zero early, so the `kzalloc`'d `struct smc_link_group` is `kfree()`d while `__smc_lgr_terminate()`, `smc_listen_work()`, and the LLC/CDC paths still dereference it \u2014 a classic use-after-free read of a generic kmalloc slab object that an attacker can reallocate and shape, leaking link-group state including `peer_systemid` and RDMA `rtokens` (remote keys/addresses).\nI:H - Post-free writes into the reallocated object include `lgr->sync_err`/`terminating` bitfields, `refcount_inc()`, and list/rb-tree manipulation, while the freed structure embeds `struct work_struct terminate_work`, `struct delayed_work free_work`, and per-link `link_down_wrk` \u2014 function pointers that `schedule_work()`/`smc_lgr_schedule_free_work()` will subsequently invoke, giving a heap-spray path to control-flow hijack.\nA:H - The commit documents real production `refcount_t: underflow`/`addition on 0` warnings in `smcr_link_put()` and `__smc_lgr_terminate()`; refcount saturation plus use of freed link-group memory yields oopses and kernel panics, and the condition is remotely and repeatably triggerable."}]}], "affected": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8", "lessThan": "f502a88fdd415647a1f2dc45fac71b9c522a052b", "versionType": "git"}, {"status": "affected", "version": "3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8", "lessThan": "0cf598548a6c36d90681d53c6b77d52363f2f295", "versionType": "git"}, {"status": "affected", "version": "3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8", "lessThan": "673d606683ac70bc074ca6676b938bff18635226", "versionType": "git"}, {"status": "affected", "version": "3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8", "lessThan": "6f0ae06a234a78ae137064f2c89135ac078a00eb", "versionType": "git"}, {"status": "affected", "version": "3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8", "lessThan": "2c7f14ed9c19ec0f149479d1c2842ec1f9bf76d7", "versionType": "git"}], "programFiles": ["net/smc/af_smc.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "4.18"}, {"status": "unaffected", "version": "0", "lessThan": "4.18", "versionType": "semver"}, {"status": "unaffected", "version": "5.15.174", "versionType": "semver", "lessThanOrEqual": "5.15.*"}, {"status": "unaffected", "version": "6.1.120", "versionType": "semver", "lessThanOrEqual": "6.1.*"}, {"status": "unaffected", "version": "6.6.66", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.5", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.13", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["net/smc/af_smc.c"], "defaultStatus": "affected"}], "references": [{"url": "https://git.kernel.org/stable/c/f502a88fdd415647a1f2dc45fac71b9c522a052b"}, {"url": "https://git.kernel.org/stable/c/0cf598548a6c36d90681d53c6b77d52363f2f295"}, {"url": "https://git.kernel.org/stable/c/673d606683ac70bc074ca6676b938bff18635226"}, {"url": "https://git.kernel.org/stable/c/6f0ae06a234a78ae137064f2c89135ac078a00eb"}, {"url": "https://git.kernel.org/stable/c/2c7f14ed9c19ec0f149479d1c2842ec1f9bf76d7"}], "x_generator": {"engine": "bippy-1.2.0"}, "descriptions": [{"lang": "en", "value": "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."}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.15.174", "versionStartIncluding": "4.18"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.1.120", "versionStartIncluding": "4.18"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.6.66", "versionStartIncluding": "4.18"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.12.5", "versionStartIncluding": "4.18"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.13", "versionStartIncluding": "4.18"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:45:38.986Z"}}}, "cveMetadata": {"cveId": "CVE-2024-56640", "state": "PUBLISHED", "dateUpdated": "2026-08-05T11:45:38.986Z", "dateReserved": "2024-12-27T15:00:39.839Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2024-12-27T15:02:42.253Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/smc/af_smc.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "f502a88fdd415647a1f2dc45fac71b9c522a052b", "status": "affected", "version": "3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8", "versionType": "git"}, {"lessThan": "0cf598548a6c36d90681d53c6b77d52363f2f295", "status": "affected", "version": "3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8", "versionType": "git"}, {"lessThan": "673d606683ac70bc074ca6676b938bff18635226", "status": "affected", "version": "3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8", "versionType": "git"}, {"lessThan": "6f0ae06a234a78ae137064f2c89135ac078a00eb", "status": "affected", "version": "3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8", "versionType": "git"}, {"lessThan": "2c7f14ed9c19ec0f149479d1c2842ec1f9bf76d7", "status": "affected", "version": "3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/smc/af_smc.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "4.18"}, {"lessThan": "4.18", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.174", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.120", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.66", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.5", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "6.13", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "A8151951-069A-4828-9C8E-5430FD2D7D67", "versionEndExcluding": "5.15.174", "versionStartIncluding": "4.18", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "09AC6122-E2A4-40FE-9D33-268A1B2EC265", "versionEndExcluding": "6.1.120", "versionStartIncluding": "5.16", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "29A976AD-B9AB-4A95-9F08-7669F8847EB9", "versionEndExcluding": "6.6.66", "versionStartIncluding": "6.2", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "9501D045-7A94-42CA-8B03-821BE94A65B7", "versionEndExcluding": "6.12.5", "versionStartIncluding": "6.7", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.13:rc1:*:*:*:*:*:*", "matchCriteriaId": "62567B3C-6CEE-46D0-BC2E-B3717FBF7D13", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: net/smc: inicializar close_work antes para evitar advertencias Encontramos una advertencia que indicaba que close_work se cancel\u00f3 antes de la inicializaci\u00f3n. ADVERTENCIA: CPU: 7 PID: 111103 en kernel/workqueue.c:3047 __flush_work+0x19e/0x1b0 Workqueue: eventos smc_lgr_terminate_work [smc] RIP: 0010:__flush_work+0x19e/0x1b0 Rastreo de llamadas: ? __wake_up_common+0x7a/0x190 ? trabajo_ocupado+0x80/0x80 __cancelar_temporizador_trabajo+0xe3/0x160 smc_cerrar_cancelar_trabajo+0x1a/0x70 [smc] smc_cerrar_aborto_activo+0x207/0x360 [smc] __smc_lgr_terminate.part.38+0xc8/0x180 [smc] proceso_uno_trabajo+0x19e/0x340 subproceso_trabajador+0x30/0x370 ? proceso_uno_trabajo+0x340/0x340 kthread+0x117/0x130 ? __kthread_cancel_work+0x50/0x50 ret_from_fork+0x22/0x30 Esto se debe a que cuando se activa smc_close_cancel_work, p. ej., el controlador RDMA es rmmod y se termina el LGR, conn->close_work se vac\u00eda antes de la inicializaci\u00f3n, lo que genera WARN_ON(!work->func). __smc_lgr_terminate | smc_connect_{rdma|ism} ------------------------------------------------------------- | smc_conn_create | \\- smc_lgr_register_conn para conn en lgr->conns_all | \\- smc_conn_kill | \\- smc_close_active_abort | \\- smc_close_cancel_work | \\- cancel_work_sync | \\- __flush_work | (close_work) | | smc_close_init | \\- INIT_WORK(&close_work) Solucione esto inicializando close_work antes de establecer la conexi\u00f3n."}], "id": "CVE-2024-56640", "lastModified": "2026-08-04T11:22:16.417", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "nvd@nist.gov", "type": "Primary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2024-56640", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2025-02-11T15:41:51.231757Z", "version": "2.0.3"}}]}, "published": "2024-12-27T15:15:23.730", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/0cf598548a6c36d90681d53c6b77d52363f2f295"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/2c7f14ed9c19ec0f149479d1c2842ec1f9bf76d7"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/673d606683ac70bc074ca6676b938bff18635226"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/6f0ae06a234a78ae137064f2c89135ac078a00eb"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/f502a88fdd415647a1f2dc45fac71b9c522a052b"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-416"}], "source": "nvd@nist.gov", "type": "Primary"}, {"description": [{"lang": "en", "value": "CWE-416"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

{"bugzilla": {"description": "kernel: net/smc: fix LGR and link use-after-free issue", "id": "2334532", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2334532"}, "csaw": false, "cvss3": {"cvss3_base_score": "6.4", "cvss3_scoring_vector": "CVSS:3.1/AV:A/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-416", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nnet/smc: fix LGR and link use-after-free issue\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.\nrefcount_t: addition on 0; use-after-free.\nWARNING: CPU: 14 PID: 107447 at lib/refcount.c:25 refcount_warn_saturate+0x9c/0x140\nWorkqueue: events smc_lgr_terminate_work [smc]\nCall trace:\nrefcount_warn_saturate+0x9c/0x140\n__smc_lgr_terminate.part.45+0x2a8/0x370 [smc]\nsmc_lgr_terminate_work+0x28/0x30 [smc]\nprocess_one_work+0x1b8/0x420\nworker_thread+0x158/0x510\nkthread+0x114/0x118\nor\nrefcount_t: underflow; use-after-free.\nWARNING: CPU: 6 PID: 93140 at lib/refcount.c:28 refcount_warn_saturate+0xf0/0x140\nWorkqueue: smc_hs_wq smc_listen_work [smc]\nCall trace:\nrefcount_warn_saturate+0xf0/0x140\nsmcr_link_put+0x1cc/0x1d8 [smc]\nsmc_conn_free+0x110/0x1b0 [smc]\nsmc_conn_abort+0x50/0x60 [smc]\nsmc_listen_find_device+0x75c/0x790 [smc]\nsmc_listen_work+0x368/0x8a0 [smc]\nprocess_one_work+0x1b8/0x420\nworker_thread+0x158/0x510\nkthread+0x114/0x118\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.\ne.g.\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)\nSo here add sock lock protection in smc_listen_work() path, making it\nexclusive with other connection operations."], "mitigation": {"lang": "en:us", "value": "To mitigate this issue, prevent module smc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically."}, "name": "CVE-2024-56640", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Will not fix", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Will not fix", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2024-12-27T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2024-56640\nhttps://nvd.nist.gov/vuln/detail/CVE-2024-56640\nhttps://lore.kernel.org/linux-cve-announce/2024122736-CVE-2024-56640-ef22@gregkh/T"], "threat_severity": "Moderate"}

{}