Date: Fri, 31 Oct 2025 19:14:44 GMT From: Michael Tuexen <tuexen@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 4b555b56edfd - stable/14 - tcp: improve credential handling in syncache Message-ID: <202510311914.59VJEilO080343@gitrepo.freebsd.org>
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The branch stable/14 has been updated by tuexen: URL: https://cgit.FreeBSD.org/src/commit/?id=4b555b56edfdd714df9010bbbb630d3d3a32f6d0 commit 4b555b56edfdd714df9010bbbb630d3d3a32f6d0 Author: Michael Tuexen <tuexen@FreeBSD.org> AuthorDate: 2025-10-27 22:28:59 +0000 Commit: Michael Tuexen <tuexen@FreeBSD.org> CommitDate: 2025-10-31 14:14:10 +0000 tcp: improve credential handling in syncache When adding a syncache entry, take a reference count of the credentials while the inp is still locked. Thanks to markj@ for providing a hint regarding the root cause. Reported by: David Marker Reviewed by: glebius Tested by: David Marker Fixes: cbc9438f0505 ("tcp: improve ref count handling when processing SYN") Sponsored by: Netflix, Inc. Differential Revision: https://reviews.freebsd.org/D53380 (cherry picked from commit 44cb1e857f048d2326bdc1a032ccd2c04d2bcdc9) --- sys/netinet/tcp_syncache.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/sys/netinet/tcp_syncache.c b/sys/netinet/tcp_syncache.c index f1402734103a..713f6a35ad45 100644 --- a/sys/netinet/tcp_syncache.c +++ b/sys/netinet/tcp_syncache.c @@ -1387,6 +1387,7 @@ syncache_add(struct in_conninfo *inc, struct tcpopt *to, struct tcphdr *th, struct tcpcb *tp; struct socket *rv = NULL; struct syncache *sc = NULL; + struct ucred *cred; struct syncache_head *sch; struct mbuf *ipopts = NULL; u_int ltflags; @@ -1415,6 +1416,7 @@ syncache_add(struct in_conninfo *inc, struct tcpopt *to, struct tcphdr *th, */ KASSERT(SOLISTENING(so), ("%s: %p not listening", __func__, so)); tp = sototcpcb(so); + cred = V_tcp_syncache.see_other ? NULL : crhold(so->so_cred); #ifdef INET6 if (inc->inc_flags & INC_ISIPV6) { @@ -1643,16 +1645,16 @@ syncache_add(struct in_conninfo *inc, struct tcpopt *to, struct tcphdr *th, /* * sc_cred is only used in syncache_pcblist() to list TCP endpoints in * TCPS_SYN_RECEIVED state when V_tcp_syncache.see_other is false. - * Therefore, store the credentials and take a reference count only - * when needed: + * Therefore, store the credentials only when needed: * - sc is allocated from the zone and not using the on stack instance. * - the sysctl variable net.inet.tcp.syncache.see_other is false. * The reference count is decremented when a zone allocated sc is * freed in syncache_free(). */ - if (sc != &scs && !V_tcp_syncache.see_other) - sc->sc_cred = crhold(so->so_cred); - else + if (sc != &scs && !V_tcp_syncache.see_other) { + sc->sc_cred = cred; + cred = NULL; + } else sc->sc_cred = NULL; sc->sc_port = port; sc->sc_ipopts = ipopts; @@ -1790,6 +1792,8 @@ donenoprobe: tcp_fastopen_decrement_counter(tfo_pending); tfo_expanded: + if (cred != NULL) + crfree(cred); if (sc == NULL || sc == &scs) { #ifdef MAC mac_syncache_destroy(&maclabel);home | help
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