GHSA-6C8W-4WVX-63Q5
Vulnerability from github – Published: 2026-09-17 18:31 – Updated: 2026-09-17 18:31In the Linux kernel, the following vulnerability has been resolved:
net/smc: release the internal TCP sock on IPPROTO_SMC socket creation failure
IPPROTO_SMC sockets create an internal TCP sock ("clcsock") from the proto->init hook. When socket creation fails after proto->init has run - e.g. a cgroup BPF program attached to BPF_CGROUP_INET_SOCK_CREATE denies the socket - sk_common_release() only invokes sk_prot->destroy if it is set, but neither smc_inet_prot nor smc_inet6_prot defines it, and smc_destruct() returns early unless sk_state is SMC_CLOSED. As a result, every failing socket(AF_INET, SOCK_STREAM, IPPROTO_SMC) call leaks one tcp_sock, so an unprivileged task able to attach a deny-all BPF_CGROUP_INET_SOCK_CREATE program to its own cgroup can grow kernel memory unboundedly.
Add a .destroy hook to both protos that releases the clcsock via smc_clcsock_release(). smc_sk_init() hashes the sock into the smc hashinfo before the clcsock is created, and smc_diag dumps walk that hash dereferencing smc->clcsock without taking clcsock_release_lock, while sk_common_release() calls .destroy before .unhash. Unhash the sock before releasing the clcsock, as __smc_release() does, so a concurrent dump cannot observe the release; the second unhash in sk_common_release() is a no-op.
{
"affected": [],
"aliases": [
"CVE-2026-90065"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-17T17:16:55Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/smc: release the internal TCP sock on IPPROTO_SMC socket creation failure\n\nIPPROTO_SMC sockets create an internal TCP sock (\"clcsock\") from the\nproto-\u003einit hook. When socket creation fails after proto-\u003einit has\nrun - e.g. a cgroup BPF program attached to BPF_CGROUP_INET_SOCK_CREATE\ndenies the socket - sk_common_release() only invokes sk_prot-\u003edestroy\nif it is set, but neither smc_inet_prot nor smc_inet6_prot defines it,\nand smc_destruct() returns early unless sk_state is SMC_CLOSED. As a\nresult, every failing socket(AF_INET, SOCK_STREAM, IPPROTO_SMC) call\nleaks one tcp_sock, so an unprivileged task able to attach a deny-all\nBPF_CGROUP_INET_SOCK_CREATE program to its own cgroup can grow kernel\nmemory unboundedly.\n\nAdd a .destroy hook to both protos that releases the clcsock via\nsmc_clcsock_release(). smc_sk_init() hashes the sock into the smc\nhashinfo before the clcsock is created, and smc_diag dumps walk that\nhash dereferencing smc-\u003eclcsock without taking clcsock_release_lock,\nwhile sk_common_release() calls .destroy before .unhash. Unhash the\nsock before releasing the clcsock, as __smc_release() does, so a\nconcurrent dump cannot observe the release; the second unhash in\nsk_common_release() is a no-op.",
"id": "GHSA-6c8w-4wvx-63q5",
"modified": "2026-09-17T18:31:49Z",
"published": "2026-09-17T18:31:49Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90065"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2f4ece7fed6d915ec64b7735962c0d84d6261032"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/84180988a455fd8e147c6b35c8df65d8b8cc76c2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/94a913cd521c0f0408820bcdbd80dadf076d97b5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cec261b0b4c5c0b044165303198d10ffcdf3414c"
}
],
"schema_version": "1.4.0",
"severity": []
}
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