Date: Tue, 09 Jun 2026 19:17:49 +0000 From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 522182827ea1 - stable/14 - in6_mcast: Fix a race in in6p_set_source_filter() Message-ID: <6a2866dd.3ebbb.42687757@gitrepo.freebsd.org>
index | next in thread | raw e-mail
The branch stable/14 has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=522182827ea173e07668b1ac40a8173c620bb99e commit 522182827ea173e07668b1ac40a8173c620bb99e Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2026-05-29 20:12:24 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2026-06-09 19:15:21 +0000 in6_mcast: Fix a race in in6p_set_source_filter() We drop the inpcb lock in order to copy in the source list, but this leaves a window where the multicast filter structure might be freed. This can be exploited to obtain root privileges. In the v4 code this race is mitigated by holding the global multicast lock across the gap. Restructure the code to copy in filters before doing anything else, so that there's no need to drop the inpcb lock and reason about the correctness of doing so. Do the same in the v4 code for consistency. Approved by: so Security: FreeBSD-SA-26:29.ip6_multicast Security: CVE-2026-49412 Reported by: Andrew Griffiths <andrew@calif.io> Reported by: Maik Münch <maik@secfault-security.com> Reviewed by: glebius Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D57347 --- sys/netinet/in_mcast.c | 40 +++++++++++++++++----------------------- sys/netinet6/in6_mcast.c | 41 +++++++++++++++++++---------------------- 2 files changed, 36 insertions(+), 45 deletions(-) diff --git a/sys/netinet/in_mcast.c b/sys/netinet/in_mcast.c index b0be48b65437..4fd00bac3ae4 100644 --- a/sys/netinet/in_mcast.c +++ b/sys/netinet/in_mcast.c @@ -2524,6 +2524,7 @@ inp_set_source_filters(struct inpcb *inp, struct sockopt *sopt) { struct epoch_tracker et; struct __msfilterreq msfr; + struct sockaddr_storage *kss; sockunion_t *gsa; struct ifnet *ifp; struct in_mfilter *imf; @@ -2536,9 +2537,6 @@ inp_set_source_filters(struct inpcb *inp, struct sockopt *sopt) if (error) return (error); - if (msfr.msfr_nsrcs > in_mcast_maxsocksrc) - return (ENOBUFS); - if ((msfr.msfr_fmode != MCAST_EXCLUDE && msfr.msfr_fmode != MCAST_INCLUDE)) return (EINVAL); @@ -2551,13 +2549,24 @@ inp_set_source_filters(struct inpcb *inp, struct sockopt *sopt) if (!IN_MULTICAST(ntohl(gsa->sin.sin_addr.s_addr))) return (EINVAL); + if (msfr.msfr_nsrcs > in_mcast_maxsocksrc) + return (ENOBUFS); + kss = mallocarray(msfr.msfr_nsrcs, sizeof(struct sockaddr_storage), + M_TEMP, M_WAITOK); + error = copyin(msfr.msfr_srcs, kss, + sizeof(struct sockaddr_storage) * msfr.msfr_nsrcs); + if (error) + goto out_inp_unlocked; + gsa->sin.sin_port = 0; /* ignore port */ NET_EPOCH_ENTER(et); ifp = ifnet_byindex(msfr.msfr_ifindex); NET_EPOCH_EXIT(et); /* XXXGL: unsafe ifp */ - if (ifp == NULL) - return (EADDRNOTAVAIL); + if (ifp == NULL) { + error = EADDRNOTAVAIL; + goto out_inp_unlocked; + } IN_MULTI_LOCK(); @@ -2589,25 +2598,9 @@ inp_set_source_filters(struct inpcb *inp, struct sockopt *sopt) if (msfr.msfr_nsrcs > 0) { struct in_msource *lims; struct sockaddr_in *psin; - struct sockaddr_storage *kss, *pkss; + struct sockaddr_storage *pkss; int i; - INP_WUNLOCK(inp); - - CTR2(KTR_IGMPV3, "%s: loading %lu source list entries", - __func__, (unsigned long)msfr.msfr_nsrcs); - kss = malloc(sizeof(struct sockaddr_storage) * msfr.msfr_nsrcs, - M_TEMP, M_WAITOK); - error = copyin(msfr.msfr_srcs, kss, - sizeof(struct sockaddr_storage) * msfr.msfr_nsrcs); - if (error) { - IN_MULTI_UNLOCK(); - free(kss, M_TEMP); - return (error); - } - - INP_WLOCK(inp); - /* * Mark all source filters as UNDEFINED at t1. * Restore new group filter mode, as imf_leave() @@ -2642,7 +2635,6 @@ inp_set_source_filters(struct inpcb *inp, struct sockopt *sopt) break; lims->imsl_st[1] = imf->imf_st[1]; } - free(kss, M_TEMP); } if (error) @@ -2679,6 +2671,8 @@ out_imf_rollback: out_inp_locked: INP_WUNLOCK(inp); IN_MULTI_UNLOCK(); +out_inp_unlocked: + free(kss, M_TEMP); return (error); } diff --git a/sys/netinet6/in6_mcast.c b/sys/netinet6/in6_mcast.c index a6186568ecb2..4ec9f36cd9ac 100644 --- a/sys/netinet6/in6_mcast.c +++ b/sys/netinet6/in6_mcast.c @@ -2489,6 +2489,7 @@ in6p_set_source_filters(struct inpcb *inp, struct sockopt *sopt) { struct __msfilterreq msfr; struct epoch_tracker et; + struct sockaddr_storage *kss; sockunion_t *gsa; struct ifnet *ifp; struct in6_mfilter *imf; @@ -2501,9 +2502,6 @@ in6p_set_source_filters(struct inpcb *inp, struct sockopt *sopt) if (error) return (error); - if (msfr.msfr_nsrcs > in6_mcast_maxsocksrc) - return (ENOBUFS); - if (msfr.msfr_fmode != MCAST_EXCLUDE && msfr.msfr_fmode != MCAST_INCLUDE) return (EINVAL); @@ -2516,19 +2514,31 @@ in6p_set_source_filters(struct inpcb *inp, struct sockopt *sopt) if (!IN6_IS_ADDR_MULTICAST(&gsa->sin6.sin6_addr)) return (EINVAL); + if (msfr.msfr_nsrcs > in6_mcast_maxsocksrc) + return (ENOBUFS); + kss = mallocarray(msfr.msfr_nsrcs, sizeof(struct sockaddr_storage), + M_TEMP, M_WAITOK); + error = copyin(msfr.msfr_srcs, kss, + sizeof(struct sockaddr_storage) * msfr.msfr_nsrcs); + if (error) + goto out_in6p_unlocked; + gsa->sin6.sin6_port = 0; /* ignore port */ NET_EPOCH_ENTER(et); ifp = ifnet_byindex(msfr.msfr_ifindex); NET_EPOCH_EXIT(et); - if (ifp == NULL) - return (EADDRNOTAVAIL); + if (ifp == NULL) { + error = EADDRNOTAVAIL; + goto out_in6p_unlocked; + } (void)in6_setscope(&gsa->sin6.sin6_addr, ifp, NULL); /* * Take the INP write lock. * Check if this socket is a member of this group. */ + IN6_MULTI_LOCK(); imo = in6p_findmoptions(inp); imf = im6o_match_group(imo, ifp, &gsa->sa); if (imf == NULL) { @@ -2553,24 +2563,9 @@ in6p_set_source_filters(struct inpcb *inp, struct sockopt *sopt) if (msfr.msfr_nsrcs > 0) { struct in6_msource *lims; struct sockaddr_in6 *psin; - struct sockaddr_storage *kss, *pkss; + struct sockaddr_storage *pkss; int i; - INP_WUNLOCK(inp); - - CTR2(KTR_MLD, "%s: loading %lu source list entries", - __func__, (unsigned long)msfr.msfr_nsrcs); - kss = malloc(sizeof(struct sockaddr_storage) * msfr.msfr_nsrcs, - M_TEMP, M_WAITOK); - error = copyin(msfr.msfr_srcs, kss, - sizeof(struct sockaddr_storage) * msfr.msfr_nsrcs); - if (error) { - free(kss, M_TEMP); - return (error); - } - - INP_WLOCK(inp); - /* * Mark all source filters as UNDEFINED at t1. * Restore new group filter mode, as im6f_leave() @@ -2615,7 +2610,6 @@ in6p_set_source_filters(struct inpcb *inp, struct sockopt *sopt) break; lims->im6sl_st[1] = imf->im6f_st[1]; } - free(kss, M_TEMP); } if (error) @@ -2650,6 +2644,9 @@ out_im6f_rollback: out_in6p_locked: INP_WUNLOCK(inp); + IN6_MULTI_UNLOCK(); +out_in6p_unlocked: + free(kss, M_TEMP); return (error); }home | help
Want to link to this message? Use this
URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?6a2866dd.3ebbb.42687757>