From ebbe4ca596daa0006d013609a8aed74220c82cfa Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Mon, 3 Jan 2022 11:21:08 +0100 Subject: [PATCH] 4.14-stable patches added patches: sctp-use-call_rcu-to-free-endpoint.patch --- .../sctp-use-call_rcu-to-free-endpoint.patch | 264 ++++++++++++++++++ queue-4.14/series | 1 + 2 files changed, 265 insertions(+) create mode 100644 queue-4.14/sctp-use-call_rcu-to-free-endpoint.patch diff --git a/queue-4.14/sctp-use-call_rcu-to-free-endpoint.patch b/queue-4.14/sctp-use-call_rcu-to-free-endpoint.patch new file mode 100644 index 00000000000..d0574e1c587 --- /dev/null +++ b/queue-4.14/sctp-use-call_rcu-to-free-endpoint.patch @@ -0,0 +1,264 @@ +From 5ec7d18d1813a5bead0b495045606c93873aecbb Mon Sep 17 00:00:00 2001 +From: Xin Long +Date: Thu, 23 Dec 2021 13:04:30 -0500 +Subject: sctp: use call_rcu to free endpoint + +From: Xin Long + +commit 5ec7d18d1813a5bead0b495045606c93873aecbb upstream. + +This patch is to delay the endpoint free by calling call_rcu() to fix +another use-after-free issue in sctp_sock_dump(): + + BUG: KASAN: use-after-free in __lock_acquire+0x36d9/0x4c20 + Call Trace: + __lock_acquire+0x36d9/0x4c20 kernel/locking/lockdep.c:3218 + lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 + __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] + _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:168 + spin_lock_bh include/linux/spinlock.h:334 [inline] + __lock_sock+0x203/0x350 net/core/sock.c:2253 + lock_sock_nested+0xfe/0x120 net/core/sock.c:2774 + lock_sock include/net/sock.h:1492 [inline] + sctp_sock_dump+0x122/0xb20 net/sctp/diag.c:324 + sctp_for_each_transport+0x2b5/0x370 net/sctp/socket.c:5091 + sctp_diag_dump+0x3ac/0x660 net/sctp/diag.c:527 + __inet_diag_dump+0xa8/0x140 net/ipv4/inet_diag.c:1049 + inet_diag_dump+0x9b/0x110 net/ipv4/inet_diag.c:1065 + netlink_dump+0x606/0x1080 net/netlink/af_netlink.c:2244 + __netlink_dump_start+0x59a/0x7c0 net/netlink/af_netlink.c:2352 + netlink_dump_start include/linux/netlink.h:216 [inline] + inet_diag_handler_cmd+0x2ce/0x3f0 net/ipv4/inet_diag.c:1170 + __sock_diag_cmd net/core/sock_diag.c:232 [inline] + sock_diag_rcv_msg+0x31d/0x410 net/core/sock_diag.c:263 + netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2477 + sock_diag_rcv+0x2a/0x40 net/core/sock_diag.c:274 + +This issue occurs when asoc is peeled off and the old sk is freed after +getting it by asoc->base.sk and before calling lock_sock(sk). + +To prevent the sk free, as a holder of the sk, ep should be alive when +calling lock_sock(). This patch uses call_rcu() and moves sock_put and +ep free into sctp_endpoint_destroy_rcu(), so that it's safe to try to +hold the ep under rcu_read_lock in sctp_transport_traverse_process(). + +If sctp_endpoint_hold() returns true, it means this ep is still alive +and we have held it and can continue to dump it; If it returns false, +it means this ep is dead and can be freed after rcu_read_unlock, and +we should skip it. + +In sctp_sock_dump(), after locking the sk, if this ep is different from +tsp->asoc->ep, it means during this dumping, this asoc was peeled off +before calling lock_sock(), and the sk should be skipped; If this ep is +the same with tsp->asoc->ep, it means no peeloff happens on this asoc, +and due to lock_sock, no peeloff will happen either until release_sock. + +Note that delaying endpoint free won't delay the port release, as the +port release happens in sctp_endpoint_destroy() before calling call_rcu(). +Also, freeing endpoint by call_rcu() makes it safe to access the sk by +asoc->base.sk in sctp_assocs_seq_show() and sctp_rcv(). + +Thanks Jones to bring this issue up. + +v1->v2: + - improve the changelog. + - add kfree(ep) into sctp_endpoint_destroy_rcu(), as Jakub noticed. + +Reported-by: syzbot+9276d76e83e3bcde6c99@syzkaller.appspotmail.com +Reported-by: Lee Jones +Fixes: d25adbeb0cdb ("sctp: fix an use-after-free issue in sctp_sock_dump") +Signed-off-by: Xin Long +Signed-off-by: David S. Miller +Signed-off-by: Greg Kroah-Hartman +--- + include/net/sctp/sctp.h | 6 +++--- + include/net/sctp/structs.h | 3 ++- + net/sctp/endpointola.c | 23 +++++++++++++++-------- + net/sctp/sctp_diag.c | 12 ++++++------ + net/sctp/socket.c | 23 +++++++++++++++-------- + 5 files changed, 41 insertions(+), 26 deletions(-) + +--- a/include/net/sctp/sctp.h ++++ b/include/net/sctp/sctp.h +@@ -118,6 +118,7 @@ extern struct percpu_counter sctp_socket + int sctp_asconf_mgmt(struct sctp_sock *, struct sctp_sockaddr_entry *); + struct sk_buff *sctp_skb_recv_datagram(struct sock *, int, int, int *); + ++typedef int (*sctp_callback_t)(struct sctp_endpoint *, struct sctp_transport *, void *); + int sctp_transport_walk_start(struct rhashtable_iter *iter); + void sctp_transport_walk_stop(struct rhashtable_iter *iter); + struct sctp_transport *sctp_transport_get_next(struct net *net, +@@ -128,9 +129,8 @@ int sctp_transport_lookup_process(int (* + struct net *net, + const union sctp_addr *laddr, + const union sctp_addr *paddr, void *p); +-int sctp_for_each_transport(int (*cb)(struct sctp_transport *, void *), +- int (*cb_done)(struct sctp_transport *, void *), +- struct net *net, int *pos, void *p); ++int sctp_transport_traverse_process(sctp_callback_t cb, sctp_callback_t cb_done, ++ struct net *net, int *pos, void *p); + int sctp_for_each_endpoint(int (*cb)(struct sctp_endpoint *, void *), void *p); + int sctp_get_sctp_info(struct sock *sk, struct sctp_association *asoc, + struct sctp_info *info); +--- a/include/net/sctp/structs.h ++++ b/include/net/sctp/structs.h +@@ -1272,6 +1272,7 @@ struct sctp_endpoint { + reconf_enable:1; + + __u8 strreset_enable; ++ struct rcu_head rcu; + }; + + /* Recover the outter endpoint structure. */ +@@ -1287,7 +1288,7 @@ static inline struct sctp_endpoint *sctp + struct sctp_endpoint *sctp_endpoint_new(struct sock *, gfp_t); + void sctp_endpoint_free(struct sctp_endpoint *); + void sctp_endpoint_put(struct sctp_endpoint *); +-void sctp_endpoint_hold(struct sctp_endpoint *); ++int sctp_endpoint_hold(struct sctp_endpoint *ep); + void sctp_endpoint_add_asoc(struct sctp_endpoint *, struct sctp_association *); + struct sctp_association *sctp_endpoint_lookup_assoc( + const struct sctp_endpoint *ep, +--- a/net/sctp/endpointola.c ++++ b/net/sctp/endpointola.c +@@ -242,6 +242,18 @@ void sctp_endpoint_free(struct sctp_endp + } + + /* Final destructor for endpoint. */ ++static void sctp_endpoint_destroy_rcu(struct rcu_head *head) ++{ ++ struct sctp_endpoint *ep = container_of(head, struct sctp_endpoint, rcu); ++ struct sock *sk = ep->base.sk; ++ ++ sctp_sk(sk)->ep = NULL; ++ sock_put(sk); ++ ++ kfree(ep); ++ SCTP_DBG_OBJCNT_DEC(ep); ++} ++ + static void sctp_endpoint_destroy(struct sctp_endpoint *ep) + { + struct sock *sk; +@@ -275,18 +287,13 @@ static void sctp_endpoint_destroy(struct + if (sctp_sk(sk)->bind_hash) + sctp_put_port(sk); + +- sctp_sk(sk)->ep = NULL; +- /* Give up our hold on the sock */ +- sock_put(sk); +- +- kfree(ep); +- SCTP_DBG_OBJCNT_DEC(ep); ++ call_rcu(&ep->rcu, sctp_endpoint_destroy_rcu); + } + + /* Hold a reference to an endpoint. */ +-void sctp_endpoint_hold(struct sctp_endpoint *ep) ++int sctp_endpoint_hold(struct sctp_endpoint *ep) + { +- refcount_inc(&ep->base.refcnt); ++ return refcount_inc_not_zero(&ep->base.refcnt); + } + + /* Release a reference to an endpoint and clean up if there are +--- a/net/sctp/sctp_diag.c ++++ b/net/sctp/sctp_diag.c +@@ -276,9 +276,8 @@ out: + return err; + } + +-static int sctp_sock_dump(struct sctp_transport *tsp, void *p) ++static int sctp_sock_dump(struct sctp_endpoint *ep, struct sctp_transport *tsp, void *p) + { +- struct sctp_endpoint *ep = tsp->asoc->ep; + struct sctp_comm_param *commp = p; + struct sock *sk = ep->base.sk; + struct sk_buff *skb = commp->skb; +@@ -288,6 +287,8 @@ static int sctp_sock_dump(struct sctp_tr + int err = 0; + + lock_sock(sk); ++ if (ep != tsp->asoc->ep) ++ goto release; + list_for_each_entry(assoc, &ep->asocs, asocs) { + if (cb->args[4] < cb->args[1]) + goto next; +@@ -330,9 +331,8 @@ release: + return err; + } + +-static int sctp_sock_filter(struct sctp_transport *tsp, void *p) ++static int sctp_sock_filter(struct sctp_endpoint *ep, struct sctp_transport *tsp, void *p) + { +- struct sctp_endpoint *ep = tsp->asoc->ep; + struct sctp_comm_param *commp = p; + struct sock *sk = ep->base.sk; + const struct inet_diag_req_v2 *r = commp->r; +@@ -490,8 +490,8 @@ skip: + if (!(idiag_states & ~(TCPF_LISTEN | TCPF_CLOSE))) + goto done; + +- sctp_for_each_transport(sctp_sock_filter, sctp_sock_dump, +- net, &pos, &commp); ++ sctp_transport_traverse_process(sctp_sock_filter, sctp_sock_dump, ++ net, &pos, &commp); + cb->args[2] = pos; + + done: +--- a/net/sctp/socket.c ++++ b/net/sctp/socket.c +@@ -4738,11 +4738,12 @@ int sctp_transport_lookup_process(int (* + } + EXPORT_SYMBOL_GPL(sctp_transport_lookup_process); + +-int sctp_for_each_transport(int (*cb)(struct sctp_transport *, void *), +- int (*cb_done)(struct sctp_transport *, void *), +- struct net *net, int *pos, void *p) { ++int sctp_transport_traverse_process(sctp_callback_t cb, sctp_callback_t cb_done, ++ struct net *net, int *pos, void *p) ++{ + struct rhashtable_iter hti; + struct sctp_transport *tsp; ++ struct sctp_endpoint *ep; + int ret; + + again: +@@ -4752,26 +4753,32 @@ again: + + tsp = sctp_transport_get_idx(net, &hti, *pos + 1); + for (; !IS_ERR_OR_NULL(tsp); tsp = sctp_transport_get_next(net, &hti)) { +- ret = cb(tsp, p); +- if (ret) +- break; ++ ep = tsp->asoc->ep; ++ if (sctp_endpoint_hold(ep)) { /* asoc can be peeled off */ ++ ret = cb(ep, tsp, p); ++ if (ret) ++ break; ++ sctp_endpoint_put(ep); ++ } + (*pos)++; + sctp_transport_put(tsp); + } + sctp_transport_walk_stop(&hti); + + if (ret) { +- if (cb_done && !cb_done(tsp, p)) { ++ if (cb_done && !cb_done(ep, tsp, p)) { + (*pos)++; ++ sctp_endpoint_put(ep); + sctp_transport_put(tsp); + goto again; + } ++ sctp_endpoint_put(ep); + sctp_transport_put(tsp); + } + + return ret; + } +-EXPORT_SYMBOL_GPL(sctp_for_each_transport); ++EXPORT_SYMBOL_GPL(sctp_transport_traverse_process); + + /* 7.2.1 Association Status (SCTP_STATUS) + diff --git a/queue-4.14/series b/queue-4.14/series index 59b2d537542..052543d413b 100644 --- a/queue-4.14/series +++ b/queue-4.14/series @@ -16,3 +16,4 @@ scsi-vmw_pvscsi-set-residual-data-length-conditionally.patch input-appletouch-initialize-work-before-device-registration.patch input-spaceball-fix-parsing-of-movement-data-packets.patch net-fix-use-after-free-in-tw_timer_handler.patch +sctp-use-call_rcu-to-free-endpoint.patch -- 2.47.3