{"id":"CVE-2025-40139","state":"PUBLISHED","title":"smc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().\n\nsmc_clc_prfx_set() is called during connect() and not under RCU\nnor RTNL.\n\nUsing sk_dst_get(sk)->dev could trigger UAF.\n\nLet's use __sk_dst_get() and dev_dst_rcu() under rcu_read_lock()\nafter kernel_getsockname().\n\nNote that the returned value of smc_clc_prfx_set() is not used\nin the caller.\n\nWhile at it, we change the 1st arg of smc_clc_prfx_set[46]_rcu()\nnot to touch dst there.","publishedAt":"2025-11-12T10:23:24.216Z","updatedAt":"2026-10-15T22:02:38.627Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"a046d57da19f812216f393e7c535f5858f793ac3","status":"affected","lessThan":"5a2fccc4b32c13ddde3676f9e15e1a9baa7d6fde","versionType":"git"},{"version":"a046d57da19f812216f393e7c535f5858f793ac3","status":"affected","lessThan":"80d1fd39f4e37d836655e9f7ffccaf78925049bf","versionType":"git"},{"version":"a046d57da19f812216f393e7c535f5858f793ac3","status":"affected","lessThan":"956c57daba55cf9ed25d9f2512883b8a1a927599","versionType":"git"},{"version":"a046d57da19f812216f393e7c535f5858f793ac3","status":"affected","lessThan":"0736993bfe5c7a9c744ae3fac62d769dfdae54e1","versionType":"git"},{"version":"a046d57da19f812216f393e7c535f5858f793ac3","status":"affected","lessThan":"935d783e5de9b64587f3adb25641dd8385e64ddb","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/smc/smc_clc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.11","versionType":"semver"},{"version":"6.1.187","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.156","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.108","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.17.3","status":"unaffected","lessThanOrEqual":"6.17.*","versionType":"semver"},{"version":"6.18","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/smc/smc_clc.c"]}],"references":["https://git.kernel.org/stable/c/5a2fccc4b32c13ddde3676f9e15e1a9baa7d6fde","https://git.kernel.org/stable/c/80d1fd39f4e37d836655e9f7ffccaf78925049bf","https://git.kernel.org/stable/c/956c57daba55cf9ed25d9f2512883b8a1a927599","https://git.kernel.org/stable/c/0736993bfe5c7a9c744ae3fac62d769dfdae54e1","https://git.kernel.org/stable/c/935d783e5de9b64587f3adb25641dd8385e64ddb"],"weaknesses":[],"ingestedAt":"2026-10-29T20:09:09.358Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/40xxx/CVE-2025-40139.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-40139","state":"PUBLISHED","datePublished":"2025-11-12T10:23:24.216Z","dateUpdated":"2026-10-15T22:02:38.627Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T07:20:57.171Z"},"containers":{"cna":{"title":"smc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().\n\nsmc_clc_prfx_set() is called during connect() and not under RCU\nnor RTNL.\n\nUsing sk_dst_get(sk)->dev could trigger UAF.\n\nLet's use __sk_dst_get() and dev_dst_rcu() under rcu_read_lock()\nafter kernel_getsockname().\n\nNote that the returned value of smc_clc_prfx_set() is not used\nin the caller.\n\nWhile at it, we change the 1st arg of smc_clc_prfx_set[46]_rcu()\nnot to touch dst there."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"a046d57da19f812216f393e7c535f5858f793ac3","status":"affected","lessThan":"5a2fccc4b32c13ddde3676f9e15e1a9baa7d6fde","versionType":"git"},{"version":"a046d57da19f812216f393e7c535f5858f793ac3","status":"affected","lessThan":"80d1fd39f4e37d836655e9f7ffccaf78925049bf","versionType":"git"},{"version":"a046d57da19f812216f393e7c535f5858f793ac3","status":"affected","lessThan":"956c57daba55cf9ed25d9f2512883b8a1a927599","versionType":"git"},{"version":"a046d57da19f812216f393e7c535f5858f793ac3","status":"affected","lessThan":"0736993bfe5c7a9c744ae3fac62d769dfdae54e1","versionType":"git"},{"version":"a046d57da19f812216f393e7c535f5858f793ac3","status":"affected","lessThan":"935d783e5de9b64587f3adb25641dd8385e64ddb","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/smc/smc_clc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.11","versionType":"semver"},{"version":"6.1.187","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.156","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.108","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.17.3","status":"unaffected","lessThanOrEqual":"6.17.*","versionType":"semver"},{"version":"6.18","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/smc/smc_clc.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/5a2fccc4b32c13ddde3676f9e15e1a9baa7d6fde"},{"url":"https://git.kernel.org/stable/c/80d1fd39f4e37d836655e9f7ffccaf78925049bf"},{"url":"https://git.kernel.org/stable/c/956c57daba55cf9ed25d9f2512883b8a1a927599"},{"url":"https://git.kernel.org/stable/c/0736993bfe5c7a9c744ae3fac62d769dfdae54e1"},{"url":"https://git.kernel.org/stable/c/935d783e5de9b64587f3adb25641dd8385e64ddb"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - `smc_clc_prfx_set()` is only reached from the client side of the CLC handshake, via `connect()` on a locally created AF_SMC socket (`smc_connect` → `__smc_connect` → `smc_clc_send_proposal`). The attacker must have local code execution to initiate the connection, so the vector is Local even though the leaked bytes are subsequently sent to a remote peer.\nAC:L - The attacker drives both sides of the race — one thread loops `connect()` on AF_SMC sockets (the stale `dst->dev` dereference), while another repeatedly creates and deletes net_devices to force `dst_dev_put()`/`free_netdev()`, which unprivileged users can do freely inside a user namespace with CAP_NET_ADMIN. No condition depends on state outside the attacker's influence, and the window is widened at will by using non-blocking connect so the work runs in `smc_connect_work`.\nPR:L - `smc_create()` performs no capability check and `MODULE_ALIAS_NETPROTO(PF_SMC)` lets any unprivileged user autoload the module; the netdev teardown side needs CAP_NET_ADMIN, which is obtainable by an ordinary user via `unshare -Urn` and therefore counts as Low, not High.\nUI:N - The attacker's own process performs every step — creating the SMC socket, connecting to a listener it controls, and tearing down the device — with no action required from any other user or administrator.\nS:U - The use-after-free touches the freed `net_device` slab and the `in_device`/`inet6_dev` structures it points to, all within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The freed `net_device` is dereferenced and its `ifa_list`/`addr_list` walked, and a reclaimed slab can be groomed with attacker-controlled data, yielding an arbitrary kernel-memory read; worse, `smc_clc_prfx_set6_rcu()` copies up to 8 prefixes out of that freed memory into the CLC Proposal that `smc_clc_send_proposal()` transmits, exfiltrating freed kernel bytes onto the wire.\nI:H - A use-after-free on a `net_device` is a heap-corruption primitive — the reclaimed object's contents are attacker-influenceable through heap spraying and the code follows pointers out of it (`dev->ip_ptr`, `dev->ip6_ptr`, list heads), which can be groomed into an arbitrary write and control-flow hijack.\nA:H - Dereferencing the freed device and walking a bogus `in_dev`/`inet6_dev` address list reliably produces a kernel oops or panic, or an unbounded list walk that hangs the CPU, and the attacker can repeat the attempt indefinitely."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-09-02T12:49:26.951Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.11","versionEndExcluding":"6.1.187"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.11","versionEndExcluding":"6.6.156"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.11","versionEndExcluding":"6.12.108"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.11","versionEndExcluding":"6.17.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.11","versionEndExcluding":"6.18"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2025-40139","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-15T21:57:12.990602Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-15T22:02:38.627Z"}}]}}}