Description
In 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.
Product status
4910280503f3af2857d5aa77e35b22d93a8960a8 (git) before f3a3f0b406b4b7eb3cea35a23fa2bf170848b104
4910280503f3af2857d5aa77e35b22d93a8960a8 (git) before 0dbc8cde64280fc37cdd678cced34eaf96cfb197
4910280503f3af2857d5aa77e35b22d93a8960a8 (git) before 0c7b55974f97b78d1109025eadf084e74cbf330f
4910280503f3af2857d5aa77e35b22d93a8960a8 (git) before 1bfb06ecb00f7fdf35dba8e8f2877346cbe5e078
4910280503f3af2857d5aa77e35b22d93a8960a8 (git) before 6187a172d6ed57d6b2c327836e4407c6456e639d
4910280503f3af2857d5aa77e35b22d93a8960a8 (git) before c9dadb31f36045a8cb65df4bd75e7237ef21a4b5
4910280503f3af2857d5aa77e35b22d93a8960a8 (git) before bf0f40d8107e2ce827521968dc6926f3e13728ae
4910280503f3af2857d5aa77e35b22d93a8960a8 (git) before abb5f36771cc4c05899b34000829a787572a8817
4.17
Any version before 4.17
5.10.258 (semver)
5.15.209 (semver)
6.1.175 (semver)
6.6.140 (semver)
6.12.90 (semver)
6.18.32 (semver)
7.0.9 (semver)
7.1-rc4 (original_commit_for_fix)
References
git.kernel.org/...c/f3a3f0b406b4b7eb3cea35a23fa2bf170848b104
git.kernel.org/...c/0dbc8cde64280fc37cdd678cced34eaf96cfb197
git.kernel.org/...c/0c7b55974f97b78d1109025eadf084e74cbf330f
git.kernel.org/...c/1bfb06ecb00f7fdf35dba8e8f2877346cbe5e078
git.kernel.org/...c/6187a172d6ed57d6b2c327836e4407c6456e639d
git.kernel.org/...c/c9dadb31f36045a8cb65df4bd75e7237ef21a4b5
git.kernel.org/...c/bf0f40d8107e2ce827521968dc6926f3e13728ae
git.kernel.org/...c/abb5f36771cc4c05899b34000829a787572a8817