FKIE_CVE-2026-64541
Vulnerability from fkie_nvd - Published: 2026-07-27 21:17 - Updated: 2026-07-30 06:25
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved:
net/smc: fix UAF in smc_cdc_rx_handler() by pinning the socket
smc_cdc_rx_handler() looks up the connection by token under the link
group's conns_lock, drops the lock, and then dereferences conn and the
smc_sock derived from it, ending in sock_hold(&smc->sk) inside
smc_cdc_msg_recv(). No reference is held across the lock release.
The only reference pinning the socket while the connection is
discoverable in the link group is taken in smc_lgr_register_conn()
(sock_hold) and dropped in __smc_lgr_unregister_conn() (sock_put), both
under conns_lock. Once the handler drops conns_lock, a concurrent
close() -> smc_release() -> smc_conn_free() -> smc_lgr_unregister_conn()
can drop that reference and free the smc_sock, so the handler's later
sock_hold() runs on freed memory:
WARNING: lib/refcount.c:25 at refcount_warn_saturate
Workqueue: rxe_wq do_work
refcount_warn_saturate (lib/refcount.c:25)
smc_cdc_msg_recv (net/smc/smc_cdc.c:430)
smc_cdc_rx_handler (net/smc/smc_cdc.c:502)
smc_wr_rx_tasklet_fn (net/smc/smc_wr.c:445)
tasklet_action_common (kernel/softirq.c:938)
handle_softirqs (kernel/softirq.c:622)
Kernel panic - not syncing: panic_on_warn set
Only SMC-R is affected. The SMC-D receive tasklet is stopped by
tasklet_kill(&conn->rx_tsklet) in smc_conn_free() before the connection
is unregistered, so it cannot run concurrently with the free.
Take the socket reference while still holding conns_lock, so the
registration reference can no longer be the last one, and drop it once
the handler is done.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/smc/smc_cdc.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "8de4f665d0febfb92803dece377791a563fc7041",
"status": "affected",
"version": "d7b0e37c1ac152905b18a5b9506179091a35b0b6",
"versionType": "git"
},
{
"lessThan": "8145b432136285e01091815b48ceb2dae261f262",
"status": "affected",
"version": "d7b0e37c1ac152905b18a5b9506179091a35b0b6",
"versionType": "git"
},
{
"lessThan": "1951bffbc6493ec34cff3956b29d4bc6606904a6",
"status": "affected",
"version": "d7b0e37c1ac152905b18a5b9506179091a35b0b6",
"versionType": "git"
},
{
"lessThan": "647b19e5cc145a2f1f685ae8ff3805a17356888c",
"status": "affected",
"version": "d7b0e37c1ac152905b18a5b9506179091a35b0b6",
"versionType": "git"
},
{
"lessThan": "472e9d7c0d5b03be3ff91ff941f57da822b031bc",
"status": "affected",
"version": "d7b0e37c1ac152905b18a5b9506179091a35b0b6",
"versionType": "git"
},
{
"lessThan": "3bfb96d9bc6a7ed0b99c7db329cc2e22a28d84bb",
"status": "affected",
"version": "d7b0e37c1ac152905b18a5b9506179091a35b0b6",
"versionType": "git"
},
{
"lessThan": "ce5aa8084329351086894aa34d77e40301d5bd3d",
"status": "affected",
"version": "d7b0e37c1ac152905b18a5b9506179091a35b0b6",
"versionType": "git"
},
{
"lessThan": "9d160b35cc34a2ba8229d07651468a7848325135",
"status": "affected",
"version": "d7b0e37c1ac152905b18a5b9506179091a35b0b6",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/smc/smc_cdc.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": "5.10.*",
"status": "unaffected",
"version": "5.10.261",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.212",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.178",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.145",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2-rc3",
"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 UAF in smc_cdc_rx_handler() by pinning the socket\n\nsmc_cdc_rx_handler() looks up the connection by token under the link\ngroup\u0027s conns_lock, drops the lock, and then dereferences conn and the\nsmc_sock derived from it, ending in sock_hold(\u0026smc-\u003esk) inside\nsmc_cdc_msg_recv(). No reference is held across the lock release.\n\nThe only reference pinning the socket while the connection is\ndiscoverable in the link group is taken in smc_lgr_register_conn()\n(sock_hold) and dropped in __smc_lgr_unregister_conn() (sock_put), both\nunder conns_lock. Once the handler drops conns_lock, a concurrent\nclose() -\u003e smc_release() -\u003e smc_conn_free() -\u003e smc_lgr_unregister_conn()\ncan drop that reference and free the smc_sock, so the handler\u0027s later\nsock_hold() runs on freed memory:\n\n WARNING: lib/refcount.c:25 at refcount_warn_saturate\n Workqueue: rxe_wq do_work\n refcount_warn_saturate (lib/refcount.c:25)\n smc_cdc_msg_recv (net/smc/smc_cdc.c:430)\n smc_cdc_rx_handler (net/smc/smc_cdc.c:502)\n smc_wr_rx_tasklet_fn (net/smc/smc_wr.c:445)\n tasklet_action_common (kernel/softirq.c:938)\n handle_softirqs (kernel/softirq.c:622)\n Kernel panic - not syncing: panic_on_warn set\n\nOnly SMC-R is affected. The SMC-D receive tasklet is stopped by\ntasklet_kill(\u0026conn-\u003erx_tsklet) in smc_conn_free() before the connection\nis unregistered, so it cannot run concurrently with the free.\n\nTake the socket reference while still holding conns_lock, so the\nregistration reference can no longer be the last one, and drop it once\nthe handler is done."
}
],
"id": "CVE-2026-64541",
"lastModified": "2026-07-30T06:25:57.950",
"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"
}
]
},
"published": "2026-07-27T21:17:06.570",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/1951bffbc6493ec34cff3956b29d4bc6606904a6"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/3bfb96d9bc6a7ed0b99c7db329cc2e22a28d84bb"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/472e9d7c0d5b03be3ff91ff941f57da822b031bc"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/647b19e5cc145a2f1f685ae8ff3805a17356888c"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/8145b432136285e01091815b48ceb2dae261f262"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/8de4f665d0febfb92803dece377791a563fc7041"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/9d160b35cc34a2ba8229d07651468a7848325135"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/ce5aa8084329351086894aa34d77e40301d5bd3d"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
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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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