GHSA-RG55-JVW9-P7M7
Vulnerability from github – Published: 2026-05-28 12:30 – Updated: 2026-05-28 12:30In the Linux kernel, the following vulnerability has been resolved:
sctp: revalidate list cursor after sctp_sendmsg_to_asoc() in SCTP_SENDALL
The SCTP_SENDALL path in sctp_sendmsg() iterates ep->asocs with list_for_each_entry_safe(), which caches the next entry in @tmp before the loop body runs. The body calls sctp_sendmsg_to_asoc(), which may drop the socket lock inside sctp_wait_for_sndbuf().
While the lock is dropped, another thread can SCTP_SOCKOPT_PEELOFF the association cached in @tmp, migrating it to a new endpoint via sctp_sock_migrate() (list_del_init() + list_add_tail() to newep->asocs), and optionally close the new socket which frees the association via kfree_rcu(). The cached @tmp can also be freed by a network ABORT for that association, processed in softirq while the lock is dropped.
sctp_wait_for_sndbuf() revalidates @asoc (the current entry) on re-lock via the "sk != asoc->base.sk" and "asoc->base.dead" checks, but nothing revalidates @tmp. After a successful return, the iterator advances to the stale @tmp, yielding either a use-after-free (if the peeled socket was closed) or a list-walk onto the new endpoint's list head (type confusion of &newep->asocs as a struct sctp_association *).
Both are reachable from CapEff=0; the type-confusion path gives controlled indirect call via the outqueue.sched->init_sid pointer.
Fix by re-deriving @tmp from @asoc after sctp_sendmsg_to_asoc() returns. @asoc is known to still be on ep->asocs at that point: the only callers that list_del an association from ep->asocs are sctp_association_free() (which sets asoc->base.dead) and sctp_assoc_migrate() (which changes asoc->base.sk), and sctp_wait_for_sndbuf() checks both under the lock before any successful return; a tripped check propagates as err < 0 and the loop bails before the re-derive.
The SCTP_ABORT path in sctp_sendmsg_check_sflags() returns 0 and the loop hits 'continue' before sctp_sendmsg_to_asoc() is ever called, so the @tmp cached by list_for_each_entry_safe() still covers the lock-held free that ba59fb027307 ("sctp: walk the list of asoc safely") was added for.
{
"affected": [],
"aliases": [
"CVE-2026-46227"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-05-28T10:16:38Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: revalidate list cursor after sctp_sendmsg_to_asoc() in SCTP_SENDALL\n\nThe SCTP_SENDALL path in sctp_sendmsg() iterates ep-\u003easocs with\nlist_for_each_entry_safe(), which caches the next entry in @tmp before\nthe loop body runs. The body calls sctp_sendmsg_to_asoc(), which may\ndrop the socket lock inside sctp_wait_for_sndbuf().\n\nWhile the lock is dropped, another thread can SCTP_SOCKOPT_PEELOFF the\nassociation cached in @tmp, migrating it to a new endpoint via\nsctp_sock_migrate() (list_del_init() + list_add_tail() to\nnewep-\u003easocs), and optionally close the new socket which frees the\nassociation via kfree_rcu(). The cached @tmp can also be freed by a\nnetwork ABORT for that association, processed in softirq while the\nlock is dropped.\n\nsctp_wait_for_sndbuf() revalidates @asoc (the current entry) on re-lock\nvia the \"sk != asoc-\u003ebase.sk\" and \"asoc-\u003ebase.dead\" checks, but nothing\nrevalidates @tmp. After a successful return, the iterator advances to\nthe stale @tmp, yielding either a use-after-free (if the peeled socket\nwas closed) or a list-walk onto the new endpoint\u0027s list head (type\nconfusion of \u0026newep-\u003easocs as a struct sctp_association *).\n\nBoth are reachable from CapEff=0; the type-confusion path gives\ncontrolled indirect call via the outqueue.sched-\u003einit_sid pointer.\n\nFix by re-deriving @tmp from @asoc after sctp_sendmsg_to_asoc()\nreturns. @asoc is known to still be on ep-\u003easocs at that point: the\nonly callers that list_del an association from ep-\u003easocs are\nsctp_association_free() (which sets asoc-\u003ebase.dead) and\nsctp_assoc_migrate() (which changes asoc-\u003ebase.sk), and\nsctp_wait_for_sndbuf() checks both under the lock before any\nsuccessful return; a tripped check propagates as err \u003c 0 and the loop\nbails before the re-derive.\n\nThe SCTP_ABORT path in sctp_sendmsg_check_sflags() returns 0 and the\nloop hits \u0027continue\u0027 before sctp_sendmsg_to_asoc() is ever called, so\nthe @tmp cached by list_for_each_entry_safe() still covers the\nlock-held free that ba59fb027307 (\"sctp: walk the list of asoc\nsafely\") was added for.",
"id": "GHSA-rg55-jvw9-p7m7",
"modified": "2026-05-28T12:30:33Z",
"published": "2026-05-28T12:30:33Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-46227"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1bfb06ecb00f7fdf35dba8e8f2877346cbe5e078"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6187a172d6ed57d6b2c327836e4407c6456e639d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/abb5f36771cc4c05899b34000829a787572a8817"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bf0f40d8107e2ce827521968dc6926f3e13728ae"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c9dadb31f36045a8cb65df4bd75e7237ef21a4b5"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
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