Anyone willing to test or ok this?
I would like to get it in before kn@ bumps ports due to net/if_var.h
changes.
On Wed, Aug 24, 2022 at 03:14:35PM +0200, Alexander Bluhm wrote:
> On Tue, Aug 23, 2022 at 02:47:11PM +0200, Stefan Sperling wrote:
> > ddb{2}> show struct ifaddr 0xffff8000004e9400
> > struct ifaddr at 0xffff8000004e9400 (64 bytes) {ifa_addr = (struct sockaddr
> > *)0
> > xdeaf0009deafbead, ifa_dstaddr = (struct sockaddr *)0x20ef1a8af1d895de,
> > ifa_net
> > mask = (struct sockaddr *)0xdeafbeaddeafbead, ifa_ifp = (struct ifnet
> > *)0xdeafb
> > eaddeafbead, ifa_list = {tqe_next = (struct ifaddr *)0xdeafbeaddeafbead,
> > tqe_pr
> > ev = 0xdeafbeaddeafbead}, ifa_flags = 0xdeafbead, ifa_refcnt = 0xdeafbead,
> > ifa_
> > metric = 0xdeafbead}
>
> The ifaddr has been freed. That should not happen, as ifafree()
> uses reference counting. But this refcount is a simple integer
> increment, that is not MP safe. In theory all ++ should be protected
> by exclusive netlock or shared netlock combiined with kernel lock.
> But maybe I missed a path.
>
> What are you doing with the machine? Forwarding, IPv6, Stress test?
> Do you have network interfaces with multiple network queues?
>
> Anyway, instead of adding kernel locks here and there, use a propper
> struct refcnt. The variable ifatrash is never read, it looks like
> a ddb debugging feature. But for debugging refcount leaks we have
> dt(4) now.
>
> enc and mpls are special, they have interface address as part of
> their sc structure. I use refcount anyway, the new panic prevents
> use after free.
>
> This has passed a full regres run.
>
> ok?
>
> bluhm
>
> Index: dev/dt/dt_prov_static.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/dev/dt/dt_prov_static.c,v
> retrieving revision 1.14
> diff -u -p -r1.14 dt_prov_static.c
> --- dev/dt/dt_prov_static.c 28 Jun 2022 09:32:27 -0000 1.14
> +++ dev/dt/dt_prov_static.c 23 Aug 2022 17:16:55 -0000
> @@ -88,9 +88,10 @@ DT_STATIC_PROBE0(smr, wakeup);
> DT_STATIC_PROBE2(smr, thread, "uint64_t", "uint64_t");
>
> /*
> - * reference counting
> + * reference counting, keep in sync with sys/refcnt.h
> */
> DT_STATIC_PROBE0(refcnt, none);
> +DT_STATIC_PROBE3(refcnt, ifaddr, "void *", "int", "int");
> DT_STATIC_PROBE3(refcnt, inpcb, "void *", "int", "int");
> DT_STATIC_PROBE3(refcnt, tdb, "void *", "int", "int");
>
> @@ -135,6 +136,7 @@ struct dt_probe *const dtps_static[] = {
> &_DT_STATIC_P(smr, thread),
> /* refcnt */
> &_DT_STATIC_P(refcnt, none),
> + &_DT_STATIC_P(refcnt, ifaddr),
> &_DT_STATIC_P(refcnt, inpcb),
> &_DT_STATIC_P(refcnt, tdb),
> };
> Index: net/if_enc.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/net/if_enc.c,v
> retrieving revision 1.78
> diff -u -p -r1.78 if_enc.c
> --- net/if_enc.c 28 Dec 2020 14:28:50 -0000 1.78
> +++ net/if_enc.c 24 Aug 2022 07:51:49 -0000
> @@ -100,6 +100,7 @@ enc_clone_create(struct if_clone *ifc, i
> * and empty ifa of type AF_LINK for this purpose.
> */
> if_alloc_sadl(ifp);
> + refcnt_init_trace(&sc->sc_ifa.ifa_refcnt, DT_REFCNT_IDX_IFADDR);
> sc->sc_ifa.ifa_ifp = ifp;
> sc->sc_ifa.ifa_addr = sdltosa(ifp->if_sadl);
> sc->sc_ifa.ifa_netmask = NULL;
> @@ -152,6 +153,10 @@ enc_clone_destroy(struct ifnet *ifp)
> NET_UNLOCK();
>
> if_detach(ifp);
> + if (refcnt_rele(&sc->sc_ifa.ifa_refcnt) == 0) {
> + panic("%s: ifa refcnt has %u refs", __func__,
> + sc->sc_ifa.ifa_refcnt.r_refs);
> + }
> free(sc, M_DEVBUF, sizeof(*sc));
>
> return (0);
> Index: net/if_mpe.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/net/if_mpe.c,v
> retrieving revision 1.101
> diff -u -p -r1.101 if_mpe.c
> --- net/if_mpe.c 8 Nov 2021 04:50:54 -0000 1.101
> +++ net/if_mpe.c 24 Aug 2022 07:52:22 -0000
> @@ -128,6 +128,7 @@ mpe_clone_create(struct if_clone *ifc, i
> sc->sc_txhprio = 0;
> sc->sc_rxhprio = IF_HDRPRIO_PACKET;
> sc->sc_rdomain = 0;
> + refcnt_init_trace(&sc->sc_ifa.ifa_refcnt, DT_REFCNT_IDX_IFADDR);
> sc->sc_ifa.ifa_ifp = ifp;
> sc->sc_ifa.ifa_addr = sdltosa(ifp->if_sadl);
> sc->sc_smpls.smpls_len = sizeof(sc->sc_smpls);
> @@ -154,6 +155,10 @@ mpe_clone_destroy(struct ifnet *ifp)
> ifq_barrier(&ifp->if_snd);
>
> if_detach(ifp);
> + if (refcnt_rele(&sc->sc_ifa.ifa_refcnt) == 0) {
> + panic("%s: ifa refcnt has %u refs", __func__,
> + sc->sc_ifa.ifa_refcnt.r_refs);
> + }
> free(sc, M_DEVBUF, sizeof *sc);
> return (0);
> }
> Index: net/if_mpip.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/net/if_mpip.c,v
> retrieving revision 1.15
> diff -u -p -r1.15 if_mpip.c
> --- net/if_mpip.c 26 Mar 2021 19:00:21 -0000 1.15
> +++ net/if_mpip.c 24 Aug 2022 07:52:26 -0000
> @@ -128,6 +128,7 @@ mpip_clone_create(struct if_clone *ifc,
> bpfattach(&ifp->if_bpf, ifp, DLT_LOOP, sizeof(uint32_t));
> #endif
>
> + refcnt_init_trace(&sc->sc_ifa.ifa_refcnt, DT_REFCNT_IDX_IFADDR);
> sc->sc_ifa.ifa_ifp = ifp;
> sc->sc_ifa.ifa_addr = sdltosa(ifp->if_sadl);
>
> @@ -152,7 +153,10 @@ mpip_clone_destroy(struct ifnet *ifp)
> ifq_barrier(&ifp->if_snd);
>
> if_detach(ifp);
> -
> + if (refcnt_rele(&sc->sc_ifa.ifa_refcnt) == 0) {
> + panic("%s: ifa refcnt has %u refs", __func__,
> + sc->sc_ifa.ifa_refcnt.r_refs);
> + }
> free(sc->sc_neighbor, M_DEVBUF, sizeof(*sc->sc_neighbor));
> free(sc, M_DEVBUF, sizeof(*sc));
>
> Index: net/if_mpw.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/net/if_mpw.c,v
> retrieving revision 1.62
> diff -u -p -r1.62 if_mpw.c
> --- net/if_mpw.c 26 Mar 2021 19:00:21 -0000 1.62
> +++ net/if_mpw.c 24 Aug 2022 07:52:00 -0000
> @@ -122,6 +122,7 @@ mpw_clone_create(struct if_clone *ifc, i
> sc->sc_txhprio = 0;
> sc->sc_rxhprio = IF_HDRPRIO_PACKET;
> sc->sc_rdomain = 0;
> + refcnt_init_trace(&sc->sc_ifa.ifa_refcnt, DT_REFCNT_IDX_IFADDR);
> sc->sc_ifa.ifa_ifp = ifp;
> sc->sc_ifa.ifa_addr = sdltosa(ifp->if_sadl);
> sc->sc_smpls.smpls_len = sizeof(sc->sc_smpls);
> @@ -149,7 +150,10 @@ mpw_clone_destroy(struct ifnet *ifp)
>
> ether_ifdetach(ifp);
> if_detach(ifp);
> -
> + if (refcnt_rele(&sc->sc_ifa.ifa_refcnt) == 0) {
> + panic("%s: ifa refcnt has %u refs", __func__,
> + sc->sc_ifa.ifa_refcnt.r_refs);
> + }
> free(sc->sc_neighbor, M_DEVBUF, sizeof(*sc->sc_neighbor));
> free(sc, M_DEVBUF, sizeof(*sc));
>
> Index: net/if_pppx.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/net/if_pppx.c,v
> retrieving revision 1.121
> diff -u -p -r1.121 if_pppx.c
> --- net/if_pppx.c 25 Jul 2022 08:29:26 -0000 1.121
> +++ net/if_pppx.c 23 Aug 2022 17:34:20 -0000
> @@ -659,6 +659,7 @@ pppx_add_session(struct pppx_dev *pxd, s
> ifaddr.sin_addr = req->pr_ip_srcaddr;
>
> ia = malloc(sizeof (*ia), M_IFADDR, M_WAITOK | M_ZERO);
> + refcnt_init_trace(&ia->ia_ifa.ifa_refcnt, DT_REFCNT_IDX_IFADDR);
>
> ia->ia_addr.sin_family = AF_INET;
> ia->ia_addr.sin_len = sizeof(struct sockaddr_in);
> Index: net/if_var.h
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/net/if_var.h,v
> retrieving revision 1.114
> diff -u -p -r1.114 if_var.h
> --- net/if_var.h 20 Feb 2021 04:55:52 -0000 1.114
> +++ net/if_var.h 23 Aug 2022 16:25:32 -0000
> @@ -242,7 +242,7 @@ struct ifaddr {
> struct ifnet *ifa_ifp; /* back-pointer to interface */
> TAILQ_ENTRY(ifaddr) ifa_list; /* list of addresses for interface */
> u_int ifa_flags; /* interface flags, see below */
> - u_int ifa_refcnt; /* number of `rt_ifa` references */
> + struct refcnt ifa_refcnt; /* number of `rt_ifa` references */
> int ifa_metric; /* cost of going out this interface */
> };
>
> @@ -333,6 +333,7 @@ int p2p_bpf_mtap(caddr_t, const struct m
> struct ifaddr *ifa_ifwithaddr(struct sockaddr *, u_int);
> struct ifaddr *ifa_ifwithdstaddr(struct sockaddr *, u_int);
> struct ifaddr *ifaof_ifpforaddr(struct sockaddr *, struct ifnet *);
> +struct ifaddr *ifaref(struct ifaddr *);
> void ifafree(struct ifaddr *);
>
> int if_isconnected(const struct ifnet *, unsigned int);
> Index: net/route.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/net/route.c,v
> retrieving revision 1.413
> diff -u -p -r1.413 route.c
> --- net/route.c 28 Jul 2022 22:19:09 -0000 1.413
> +++ net/route.c 23 Aug 2022 16:31:29 -0000
> @@ -146,7 +146,6 @@ extern unsigned int rtmap_limit;
>
> struct cpumem * rtcounters;
> int rttrash; /* routes not in table but not freed */
> -int ifatrash; /* ifas not in ifp list but not free */
>
> struct pool rtentry_pool; /* pool for rtentry structures */
> struct pool rttimer_pool; /* pool for rttimer structures */
> @@ -512,16 +511,19 @@ rtfree(struct rtentry *rt)
> pool_put(&rtentry_pool, rt);
> }
>
> +struct ifaddr *
> +ifaref(struct ifaddr *ifa)
> +{
> + refcnt_take(&ifa->ifa_refcnt);
> + return ifa;
> +}
> +
> void
> ifafree(struct ifaddr *ifa)
> {
> - if (ifa == NULL)
> - panic("ifafree");
> - if (ifa->ifa_refcnt == 0) {
> - ifatrash--;
> - free(ifa, M_IFADDR, 0);
> - } else
> - ifa->ifa_refcnt--;
> + if (refcnt_rele(&ifa->ifa_refcnt) == 0)
> + return;
> + free(ifa, M_IFADDR, 0);
> }
>
> /*
> @@ -901,8 +903,7 @@ rtrequest(int req, struct rt_addrinfo *i
> rt_mpls_clear(rt);
> #endif
>
> - ifa->ifa_refcnt++;
> - rt->rt_ifa = ifa;
> + rt->rt_ifa = ifaref(ifa);
> rt->rt_ifidx = ifp->if_index;
> /*
> * Copy metrics and a back pointer from the cloned
> @@ -1857,8 +1858,8 @@ db_print_ifa(struct ifaddr *ifa)
> db_print_sa(ifa->ifa_dstaddr);
> db_printf(" ifa_mask=");
> db_print_sa(ifa->ifa_netmask);
> - db_printf(" flags=0x%x, refcnt=%d, metric=%d\n",
> - ifa->ifa_flags, ifa->ifa_refcnt, ifa->ifa_metric);
> + db_printf(" flags=0x%x, refcnt=%u, metric=%d\n",
> + ifa->ifa_flags, ifa->ifa_refcnt.r_refs, ifa->ifa_metric);
> }
>
> /*
> Index: net/rtsock.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/net/rtsock.c,v
> retrieving revision 1.341
> diff -u -p -r1.341 rtsock.c
> --- net/rtsock.c 22 Aug 2022 21:18:48 -0000 1.341
> +++ net/rtsock.c 23 Aug 2022 16:27:03 -0000
> @@ -1115,8 +1115,7 @@ rtm_output(struct rt_msghdr *rtm, struct
> ifp->if_rtrequest(ifp, RTM_DELETE, rt);
> ifafree(rt->rt_ifa);
>
> - ifa->ifa_refcnt++;
> - rt->rt_ifa = ifa;
> + rt->rt_ifa = ifaref(ifa);
> rt->rt_ifidx = ifa->ifa_ifp->if_index;
> /* recheck link state after ifp change */
> rt_if_linkstate_change(rt, ifa->ifa_ifp,
> Index: netinet/in.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/in.c,v
> retrieving revision 1.175
> diff -u -p -r1.175 in.c
> --- netinet/in.c 6 Aug 2022 15:57:59 -0000 1.175
> +++ netinet/in.c 23 Aug 2022 16:59:09 -0000
> @@ -379,6 +379,7 @@ in_ioctl_set_ifaddr(u_long cmd, caddr_t
> }
> if (ia == NULL) {
> ia = malloc(sizeof *ia, M_IFADDR, M_WAITOK | M_ZERO);
> + refcnt_init_trace(&ia->ia_ifa.ifa_refcnt, DT_REFCNT_IDX_IFADDR);
> ia->ia_addr.sin_family = AF_INET;
> ia->ia_addr.sin_len = sizeof(ia->ia_addr);
> ia->ia_ifa.ifa_addr = sintosa(&ia->ia_addr);
> @@ -475,6 +476,8 @@ in_ioctl_change_ifaddr(u_long cmd, caddr
>
> if (ia == NULL) {
> ia = malloc(sizeof *ia, M_IFADDR, M_WAITOK | M_ZERO);
> + refcnt_init_trace(&ia->ia_ifa.ifa_refcnt,
> + DT_REFCNT_IDX_IFADDR);
> ia->ia_addr.sin_family = AF_INET;
> ia->ia_addr.sin_len = sizeof(ia->ia_addr);
> ia->ia_ifa.ifa_addr = sintosa(&ia->ia_addr);
> @@ -745,7 +748,6 @@ in_purgeaddr(struct ifaddr *ifa)
> {
> struct ifnet *ifp = ifa->ifa_ifp;
> struct in_ifaddr *ia = ifatoia(ifa);
> - extern int ifatrash;
>
> NET_ASSERT_LOCKED();
>
> @@ -760,7 +762,6 @@ in_purgeaddr(struct ifaddr *ifa)
> ia->ia_allhosts = NULL;
> }
>
> - ifatrash++;
> ia->ia_ifp = NULL;
> ifafree(&ia->ia_ifa);
> }
> Index: netinet6/in6.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/in6.c,v
> retrieving revision 1.247
> diff -u -p -r1.247 in6.c
> --- netinet6/in6.c 6 Aug 2022 15:57:59 -0000 1.247
> +++ netinet6/in6.c 23 Aug 2022 16:55:17 -0000
> @@ -647,6 +647,8 @@ in6_update_ifa(struct ifnet *ifp, struct
> if (ia6 == NULL) {
> hostIsNew = 1;
> ia6 = malloc(sizeof(*ia6), M_IFADDR, M_WAITOK | M_ZERO);
> + refcnt_init_trace(&ia6->ia_ifa.ifa_refcnt,
> + DT_REFCNT_IDX_IFADDR);
> LIST_INIT(&ia6->ia6_memberships);
> /* Initialize the address and masks, and put time stamp */
> ia6->ia_ifa.ifa_addr = sin6tosa(&ia6->ia_addr);
> @@ -938,7 +940,6 @@ void
> in6_unlink_ifa(struct in6_ifaddr *ia6, struct ifnet *ifp)
> {
> struct ifaddr *ifa = &ia6->ia_ifa;
> - extern int ifatrash;
> int plen;
>
> NET_ASSERT_LOCKED();
> @@ -953,7 +954,6 @@ in6_unlink_ifa(struct in6_ifaddr *ia6, s
> rt_ifa_purge(ifa);
> ifa_del(ifp, ifa);
>
> - ifatrash++;
> ia6->ia_ifp = NULL;
> ifafree(&ia6->ia_ifa);
> }
> Index: netinet6/nd6_nbr.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/nd6_nbr.c,v
> retrieving revision 1.132
> diff -u -p -r1.132 nd6_nbr.c
> --- netinet6/nd6_nbr.c 8 Aug 2022 17:47:59 -0000 1.132
> +++ netinet6/nd6_nbr.c 23 Aug 2022 16:27:11 -0000
> @@ -1124,8 +1124,7 @@ nd6_dad_start(struct ifaddr *ifa)
> * first packet to be sent from the interface after interface
> * (re)initialization.
> */
> - dp->dad_ifa = ifa;
> - ifa->ifa_refcnt++; /* just for safety */
> + dp->dad_ifa = ifaref(ifa);
> dp->dad_count = ip6_dad_count;
> dp->dad_ns_icount = dp->dad_na_icount = 0;
> dp->dad_ns_ocount = dp->dad_ns_tcount = 0;
> Index: sys/refcnt.h
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/sys/refcnt.h,v
> retrieving revision 1.7
> diff -u -p -r1.7 refcnt.h
> --- sys/refcnt.h 28 Jun 2022 09:32:28 -0000 1.7
> +++ sys/refcnt.h 23 Aug 2022 16:54:02 -0000
> @@ -43,8 +43,10 @@ void refcnt_finalize(struct refcnt *, co
> int refcnt_shared(struct refcnt *);
> unsigned int refcnt_read(struct refcnt *);
>
> -#define DT_REFCNT_IDX_INPCB 1
> -#define DT_REFCNT_IDX_TDB 2
> +/* sorted alphabetically, keep in sync with dev/dt/dt_prov_static.c */
> +#define DT_REFCNT_IDX_IFADDR 1
> +#define DT_REFCNT_IDX_INPCB 2
> +#define DT_REFCNT_IDX_TDB 3
>
> #endif /* _KERNEL */
>
