CVE-2025-40012 (GCVE-0-2025-40012)
Vulnerability from cvelistv5 – Published: 2025-10-20 15:26 – Updated: 2026-08-05 12:07
VLAI
EPSS
VEX
Title
net/smc: fix warning in smc_rx_splice() when calling get_page()
Summary
In the Linux kernel, the following vulnerability has been resolved:
net/smc: fix warning in smc_rx_splice() when calling get_page()
smc_lo_register_dmb() allocates DMB buffers with kzalloc(), which are
later passed to get_page() in smc_rx_splice(). Since kmalloc memory is
not page-backed, this triggers WARN_ON_ONCE() in get_page() and prevents
holding a refcount on the buffer. This can lead to use-after-free if
the memory is released before splice_to_pipe() completes.
Use folio_alloc() instead, ensuring DMBs are page-backed and safe for
get_page().
WARNING: CPU: 18 PID: 12152 at ./include/linux/mm.h:1330 smc_rx_splice+0xaf8/0xe20 [smc]
CPU: 18 UID: 0 PID: 12152 Comm: smcapp Kdump: loaded Not tainted 6.17.0-rc3-11705-g9cf4672ecfee #10 NONE
Hardware name: IBM 3931 A01 704 (z/VM 7.4.0)
Krnl PSW : 0704e00180000000 000793161032696c (smc_rx_splice+0xafc/0xe20 [smc])
R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3
Krnl GPRS: 0000000000000000 001cee80007d3001 00077400000000f8 0000000000000005
0000000000000001 001cee80007d3006 0007740000001000 001c000000000000
000000009b0c99e0 0000000000001000 001c0000000000f8 001c000000000000
000003ffcc6f7c88 0007740003e98000 0007931600000005 000792969b2ff7b8
Krnl Code: 0007931610326960: af000000 mc 0,0
0007931610326964: a7f4ff43 brc 15,00079316103267ea
#0007931610326968: af000000 mc 0,0
>000793161032696c: a7f4ff3f brc 15,00079316103267ea
0007931610326970: e320f1000004 lg %r2,256(%r15)
0007931610326976: c0e53fd1b5f5 brasl %r14,000793168fd5d560
000793161032697c: a7f4fbb5 brc 15,00079316103260e6
0007931610326980: b904002b lgr %r2,%r11
Call Trace:
smc_rx_splice+0xafc/0xe20 [smc]
smc_rx_splice+0x756/0xe20 [smc])
smc_rx_recvmsg+0xa74/0xe00 [smc]
smc_splice_read+0x1ce/0x3b0 [smc]
sock_splice_read+0xa2/0xf0
do_splice_read+0x198/0x240
splice_file_to_pipe+0x7e/0x110
do_splice+0x59e/0xde0
__do_splice+0x11a/0x2d0
__s390x_sys_splice+0x140/0x1f0
__do_syscall+0x122/0x280
system_call+0x6e/0x90
Last Breaking-Event-Address:
smc_rx_splice+0x960/0xe20 [smc]
---[ end trace 0000000000000000 ]---
Severity
7.8 (High)
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
f7a22071dbf316c982fb44308874bd7ad9ac2091 , < 14fc4fdae42e34d7ee871b292ac2ecc61c2c5de7
(git)
Affected: f7a22071dbf316c982fb44308874bd7ad9ac2091 , < d5411685dc2f6ac7bdf01a0a204d56cae38c6cf6 (git) Affected: f7a22071dbf316c982fb44308874bd7ad9ac2091 , < a35c04de2565db191726b5741e6b66a35002c652 (git) |
guessed | |
| Linux | Linux |
Affected:
6.10
Unaffected: 0 , < 6.10 (semver) Unaffected: 6.12.50 , ≤ 6.12.* (semver) Unaffected: 6.16.10 , ≤ 6.16.* (semver) Unaffected: 6.17 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/smc/smc_loopback.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "14fc4fdae42e34d7ee871b292ac2ecc61c2c5de7",
"status": "affected",
"version": "f7a22071dbf316c982fb44308874bd7ad9ac2091",
"versionType": "git"
},
{
"lessThan": "d5411685dc2f6ac7bdf01a0a204d56cae38c6cf6",
"status": "affected",
"version": "f7a22071dbf316c982fb44308874bd7ad9ac2091",
"versionType": "git"
},
{
"lessThan": "a35c04de2565db191726b5741e6b66a35002c652",
"status": "affected",
"version": "f7a22071dbf316c982fb44308874bd7ad9ac2091",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/smc/smc_loopback.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.10"
},
{
"lessThan": "6.10",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.50",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.16.*",
"status": "unaffected",
"version": "6.16.10",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.17",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.50",
"versionStartIncluding": "6.10",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.16.10",
"versionStartIncluding": "6.10",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.17",
"versionStartIncluding": "6.10",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/smc: fix warning in smc_rx_splice() when calling get_page()\n\nsmc_lo_register_dmb() allocates DMB buffers with kzalloc(), which are\nlater passed to get_page() in smc_rx_splice(). Since kmalloc memory is\nnot page-backed, this triggers WARN_ON_ONCE() in get_page() and prevents\nholding a refcount on the buffer. This can lead to use-after-free if\nthe memory is released before splice_to_pipe() completes.\n\nUse folio_alloc() instead, ensuring DMBs are page-backed and safe for\nget_page().\n\nWARNING: CPU: 18 PID: 12152 at ./include/linux/mm.h:1330 smc_rx_splice+0xaf8/0xe20 [smc]\nCPU: 18 UID: 0 PID: 12152 Comm: smcapp Kdump: loaded Not tainted 6.17.0-rc3-11705-g9cf4672ecfee #10 NONE\nHardware name: IBM 3931 A01 704 (z/VM 7.4.0)\nKrnl PSW : 0704e00180000000 000793161032696c (smc_rx_splice+0xafc/0xe20 [smc])\n R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3\nKrnl GPRS: 0000000000000000 001cee80007d3001 00077400000000f8 0000000000000005\n 0000000000000001 001cee80007d3006 0007740000001000 001c000000000000\n 000000009b0c99e0 0000000000001000 001c0000000000f8 001c000000000000\n 000003ffcc6f7c88 0007740003e98000 0007931600000005 000792969b2ff7b8\nKrnl Code: 0007931610326960: af000000\t\tmc\t0,0\n 0007931610326964: a7f4ff43\t\tbrc\t15,00079316103267ea\n #0007931610326968: af000000\t\tmc\t0,0\n \u003e000793161032696c: a7f4ff3f\t\tbrc\t15,00079316103267ea\n 0007931610326970: e320f1000004\tlg\t%r2,256(%r15)\n 0007931610326976: c0e53fd1b5f5\tbrasl\t%r14,000793168fd5d560\n 000793161032697c: a7f4fbb5\t\tbrc\t15,00079316103260e6\n 0007931610326980: b904002b\t\tlgr\t%r2,%r11\nCall Trace:\n smc_rx_splice+0xafc/0xe20 [smc]\n smc_rx_splice+0x756/0xe20 [smc])\n smc_rx_recvmsg+0xa74/0xe00 [smc]\n smc_splice_read+0x1ce/0x3b0 [smc]\n sock_splice_read+0xa2/0xf0\n do_splice_read+0x198/0x240\n splice_file_to_pipe+0x7e/0x110\n do_splice+0x59e/0xde0\n __do_splice+0x11a/0x2d0\n __s390x_sys_splice+0x140/0x1f0\n __do_syscall+0x122/0x280\n system_call+0x6e/0x90\nLast Breaking-Event-Address:\nsmc_rx_splice+0x960/0xe20 [smc]\n---[ end trace 0000000000000000 ]---"
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The vulnerable path is reached via the splice() syscall on a local AF_SMC socket, and loopback-ism explicitly rejects any peer whose GID differs from the local GID (smc_lo_query_rgid), so both endpoints must be on the same host. No remote or adjacent packet can reach smc_lo_register_dmb().\nAC:L - The attacker deterministically controls the entire sequence \u2014 establish a loopback AF_SMC connection, send data, splice it into a pipe, close the sockets to free the DMB, then read the pipe; no race window or attacker-uninfluenceable state is required. Heap reuse of the freed 16 KB\u20131 MB region is groomable from userspace.\nPR:L - There is no capability check anywhere on the path: socket(AF_SMC) (which even autoloads the module without CAP_NET_ADMIN), connect/listen on 127.0.0.1, and splice() are all available to any unprivileged local user. No root or namespace privilege is needed.\nUI:N - A single unprivileged process can act as both SMC client and server on loopback and drive the whole sequence itself. No victim action or interaction is involved.\nS:U - The corruption is confined to kernel memory managed by the same kernel security authority; there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - Because get_page() takes no reference, the DMB can be kvfree()\u0027d while the pipe still points at it; subsequently reading or re-splicing the pipe copies whatever now occupies those reallocated pages (up to the full DMB size) straight to userspace, yielding a large arbitrary kernel-heap disclosure.\nI:H - This is a use-after-free on page-granular memory, and smc_rx_pipe_buf_release() additionally issues put_page() on a page it never referenced \u2014 once the page is recycled the folio is no longer large_kmalloc, so the refcount of an unrelated owner\u0027s page is decremented, causing a premature free and page reuse that is a well-known route to arbitrary write and privilege escalation.\nA:H - The WARN_ON_ONCE in get_page() fires (an immediate panic on the many deployments running panic_on_warn=1), and the resulting use-after-free plus page refcount underflow readily produce oopses, memory corruption, and kernel panics."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-05T12:07:04.409Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/14fc4fdae42e34d7ee871b292ac2ecc61c2c5de7"
},
{
"url": "https://git.kernel.org/stable/c/d5411685dc2f6ac7bdf01a0a204d56cae38c6cf6"
},
{
"url": "https://git.kernel.org/stable/c/a35c04de2565db191726b5741e6b66a35002c652"
}
],
"title": "net/smc: fix warning in smc_rx_splice() when calling get_page()",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2025-40012",
"datePublished": "2025-10-20T15:26:57.214Z",
"dateReserved": "2025-04-16T07:20:57.151Z",
"dateUpdated": "2026-08-05T12:07:04.409Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2025-40012",
"date": "2026-09-19",
"epss": "0.00179",
"percentile": "0.07684"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/smc/smc_loopback.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "14fc4fdae42e34d7ee871b292ac2ecc61c2c5de7",
"status": "affected",
"version": "f7a22071dbf316c982fb44308874bd7ad9ac2091",
"versionType": "git"
},
{
"lessThan": "d5411685dc2f6ac7bdf01a0a204d56cae38c6cf6",
"status": "affected",
"version": "f7a22071dbf316c982fb44308874bd7ad9ac2091",
"versionType": "git"
},
{
"lessThan": "a35c04de2565db191726b5741e6b66a35002c652",
"status": "affected",
"version": "f7a22071dbf316c982fb44308874bd7ad9ac2091",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/smc/smc_loopback.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.10"
},
{
"lessThan": "6.10",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.50",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.16.*",
"status": "unaffected",
"version": "6.16.10",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.17",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/smc: fix warning in smc_rx_splice() when calling get_page()\n\nsmc_lo_register_dmb() allocates DMB buffers with kzalloc(), which are\nlater passed to get_page() in smc_rx_splice(). Since kmalloc memory is\nnot page-backed, this triggers WARN_ON_ONCE() in get_page() and prevents\nholding a refcount on the buffer. This can lead to use-after-free if\nthe memory is released before splice_to_pipe() completes.\n\nUse folio_alloc() instead, ensuring DMBs are page-backed and safe for\nget_page().\n\nWARNING: CPU: 18 PID: 12152 at ./include/linux/mm.h:1330 smc_rx_splice+0xaf8/0xe20 [smc]\nCPU: 18 UID: 0 PID: 12152 Comm: smcapp Kdump: loaded Not tainted 6.17.0-rc3-11705-g9cf4672ecfee #10 NONE\nHardware name: IBM 3931 A01 704 (z/VM 7.4.0)\nKrnl PSW : 0704e00180000000 000793161032696c (smc_rx_splice+0xafc/0xe20 [smc])\n R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3\nKrnl GPRS: 0000000000000000 001cee80007d3001 00077400000000f8 0000000000000005\n 0000000000000001 001cee80007d3006 0007740000001000 001c000000000000\n 000000009b0c99e0 0000000000001000 001c0000000000f8 001c000000000000\n 000003ffcc6f7c88 0007740003e98000 0007931600000005 000792969b2ff7b8\nKrnl Code: 0007931610326960: af000000\t\tmc\t0,0\n 0007931610326964: a7f4ff43\t\tbrc\t15,00079316103267ea\n #0007931610326968: af000000\t\tmc\t0,0\n \u003e000793161032696c: a7f4ff3f\t\tbrc\t15,00079316103267ea\n 0007931610326970: e320f1000004\tlg\t%r2,256(%r15)\n 0007931610326976: c0e53fd1b5f5\tbrasl\t%r14,000793168fd5d560\n 000793161032697c: a7f4fbb5\t\tbrc\t15,00079316103260e6\n 0007931610326980: b904002b\t\tlgr\t%r2,%r11\nCall Trace:\n smc_rx_splice+0xafc/0xe20 [smc]\n smc_rx_splice+0x756/0xe20 [smc])\n smc_rx_recvmsg+0xa74/0xe00 [smc]\n smc_splice_read+0x1ce/0x3b0 [smc]\n sock_splice_read+0xa2/0xf0\n do_splice_read+0x198/0x240\n splice_file_to_pipe+0x7e/0x110\n do_splice+0x59e/0xde0\n __do_splice+0x11a/0x2d0\n __s390x_sys_splice+0x140/0x1f0\n __do_syscall+0x122/0x280\n system_call+0x6e/0x90\nLast Breaking-Event-Address:\nsmc_rx_splice+0x960/0xe20 [smc]\n---[ end trace 0000000000000000 ]---"
}
],
"id": "CVE-2025-40012",
"lastModified": "2026-07-30T06:24:06.137",
"metrics": {
"cvssMetricV31": [
{
"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": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2025-10-20T16:15:37.937",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/14fc4fdae42e34d7ee871b292ac2ecc61c2c5de7"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/a35c04de2565db191726b5741e6b66a35002c652"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/d5411685dc2f6ac7bdf01a0a204d56cae38c6cf6"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Deferred"
}
},
"redhat_vex": {
"aggregate_severity": "None",
"current_release_date": "2026-06-30T10:31:12+00:00",
"cve": "CVE-2025-40012",
"id": "CVE-2025-40012",
"initial_release_date": "2025-10-20T00:00:00+00:00",
"product_status:known_not_affected": "274",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: net/smc: fix warning in smc_rx_splice() when calling get_page()",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-40012.json",
"version": "3"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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