From d5f9023fa61ee8b94f37a93f08e94b136cf1e463 Mon Sep 17 00:00:00 2001 From: Thadeu Lima de Souza Cascardo Date: Sat, 19 Jun 2021 13:18:13 -0300 Subject: [PATCH 1/5] can: bcm: delay release of struct bcm_op after synchronize_rcu() can_rx_register() callbacks may be called concurrently to the call to can_rx_unregister(). The callbacks and callback data, though, are protected by RCU and the struct sock reference count. So the callback data is really attached to the life of sk, meaning that it should be released on sk_destruct. However, bcm_remove_op() calls tasklet_kill(), and RCU callbacks may be called under RCU softirq, so that cannot be used on kernels before the introduction of HRTIMER_MODE_SOFT. However, bcm_rx_handler() is called under RCU protection, so after calling can_rx_unregister(), we may call synchronize_rcu() in order to wait for any RCU read-side critical sections to finish. That is, bcm_rx_handler() won't be called anymore for those ops. So, we only free them, after we do that synchronize_rcu(). Fixes: ffd980f976e7 ("[CAN]: Add broadcast manager (bcm) protocol") Link: https://lore.kernel.org/r/20210619161813.2098382-1-cascardo@canonical.com Cc: linux-stable Reported-by: syzbot+0f7e7e5e2f4f40fa89c0@syzkaller.appspotmail.com Reported-by: Norbert Slusarek Signed-off-by: Thadeu Lima de Souza Cascardo Acked-by: Oliver Hartkopp Signed-off-by: Marc Kleine-Budde --- net/can/bcm.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/can/bcm.c b/net/can/bcm.c index f3e4d9528fa3..0928a39c4423 100644 --- a/net/can/bcm.c +++ b/net/can/bcm.c @@ -785,6 +785,7 @@ static int bcm_delete_rx_op(struct list_head *ops, struct bcm_msg_head *mh, bcm_rx_handler, op); list_del(&op->list); + synchronize_rcu(); bcm_remove_op(op); return 1; /* done */ } @@ -1533,9 +1534,13 @@ static int bcm_release(struct socket *sock) REGMASK(op->can_id), bcm_rx_handler, op); - bcm_remove_op(op); } + synchronize_rcu(); + + list_for_each_entry_safe(op, next, &bo->rx_ops, list) + bcm_remove_op(op); + #if IS_ENABLED(CONFIG_PROC_FS) /* remove procfs entry */ if (net->can.bcmproc_dir && bo->bcm_proc_read) From fb8696ab14adadb2e3f6c17c18ed26b3ecd96691 Mon Sep 17 00:00:00 2001 From: Oliver Hartkopp Date: Fri, 18 Jun 2021 19:36:45 +0200 Subject: [PATCH 2/5] can: gw: synchronize rcu operations before removing gw job entry can_can_gw_rcv() is called under RCU protection, so after calling can_rx_unregister(), we have to call synchronize_rcu in order to wait for any RCU read-side critical sections to finish before removing the kmem_cache entry with the referenced gw job entry. Link: https://lore.kernel.org/r/20210618173645.2238-1-socketcan@hartkopp.net Fixes: c1aabdf379bc ("can-gw: add netlink based CAN routing") Cc: linux-stable Signed-off-by: Oliver Hartkopp Signed-off-by: Marc Kleine-Budde --- net/can/gw.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/can/gw.c b/net/can/gw.c index ba4124805602..d8861e862f15 100644 --- a/net/can/gw.c +++ b/net/can/gw.c @@ -596,6 +596,7 @@ static int cgw_notifier(struct notifier_block *nb, if (gwj->src.dev == dev || gwj->dst.dev == dev) { hlist_del(&gwj->list); cgw_unregister_filter(net, gwj); + synchronize_rcu(); kmem_cache_free(cgw_cache, gwj); } } @@ -1154,6 +1155,7 @@ static void cgw_remove_all_jobs(struct net *net) hlist_for_each_entry_safe(gwj, nx, &net->can.cgw_list, list) { hlist_del(&gwj->list); cgw_unregister_filter(net, gwj); + synchronize_rcu(); kmem_cache_free(cgw_cache, gwj); } } @@ -1222,6 +1224,7 @@ static int cgw_remove_job(struct sk_buff *skb, struct nlmsghdr *nlh, hlist_del(&gwj->list); cgw_unregister_filter(net, gwj); + synchronize_rcu(); kmem_cache_free(cgw_cache, gwj); err = 0; break; From 14a4696bc3118ba49da28f79280e1d55603aa737 Mon Sep 17 00:00:00 2001 From: Oliver Hartkopp Date: Fri, 18 Jun 2021 19:37:13 +0200 Subject: [PATCH 3/5] can: isotp: isotp_release(): omit unintended hrtimer restart on socket release When closing the isotp socket, the potentially running hrtimers are canceled before removing the subscription for CAN identifiers via can_rx_unregister(). This may lead to an unintended (re)start of a hrtimer in isotp_rcv_cf() and isotp_rcv_fc() in the case that a CAN frame is received by isotp_rcv() while the subscription removal is processed. However, isotp_rcv() is called under RCU protection, so after calling can_rx_unregister, we may call synchronize_rcu in order to wait for any RCU read-side critical sections to finish. This prevents the reception of CAN frames after hrtimer_cancel() and therefore the unintended (re)start of the hrtimers. Link: https://lore.kernel.org/r/20210618173713.2296-1-socketcan@hartkopp.net Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol") Cc: linux-stable Signed-off-by: Oliver Hartkopp Signed-off-by: Marc Kleine-Budde --- net/can/isotp.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/can/isotp.c b/net/can/isotp.c index be6183f8ca11..234cc4ad179a 100644 --- a/net/can/isotp.c +++ b/net/can/isotp.c @@ -1028,9 +1028,6 @@ static int isotp_release(struct socket *sock) lock_sock(sk); - hrtimer_cancel(&so->txtimer); - hrtimer_cancel(&so->rxtimer); - /* remove current filters & unregister */ if (so->bound && (!(so->opt.flags & CAN_ISOTP_SF_BROADCAST))) { if (so->ifindex) { @@ -1042,10 +1039,14 @@ static int isotp_release(struct socket *sock) SINGLE_MASK(so->rxid), isotp_rcv, sk); dev_put(dev); + synchronize_rcu(); } } } + hrtimer_cancel(&so->txtimer); + hrtimer_cancel(&so->rxtimer); + so->ifindex = 0; so->bound = 0; From 22c696fed25c63c7f67508309820358b94a96b6d Mon Sep 17 00:00:00 2001 From: Oleksij Rempel Date: Thu, 17 Jun 2021 15:06:23 +0200 Subject: [PATCH 4/5] can: j1939: j1939_sk_init(): set SOCK_RCU_FREE to call sk_destruct() after RCU is done Set SOCK_RCU_FREE to let RCU to call sk_destruct() on completion. Without this patch, we will run in to j1939_can_recv() after priv was freed by j1939_sk_release()->j1939_sk_sock_destruct() Fixes: 25fe97cb7620 ("can: j1939: move j1939_priv_put() into sk_destruct callback") Link: https://lore.kernel.org/r/20210617130623.12705-1-o.rempel@pengutronix.de Cc: linux-stable Reported-by: Thadeu Lima de Souza Cascardo Reported-by: syzbot+bdf710cfc41c186fdff3@syzkaller.appspotmail.com Signed-off-by: Oleksij Rempel Signed-off-by: Marc Kleine-Budde --- net/can/j1939/main.c | 4 ++++ net/can/j1939/socket.c | 3 +++ 2 files changed, 7 insertions(+) diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c index da3a7a7bcff2..08c8606cfd9c 100644 --- a/net/can/j1939/main.c +++ b/net/can/j1939/main.c @@ -193,6 +193,10 @@ static void j1939_can_rx_unregister(struct j1939_priv *priv) can_rx_unregister(dev_net(ndev), ndev, J1939_CAN_ID, J1939_CAN_MASK, j1939_can_recv, priv); + /* The last reference of priv is dropped by the RCU deferred + * j1939_sk_sock_destruct() of the last socket, so we can + * safely drop this reference here. + */ j1939_priv_put(priv); } diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c index 56aa66147d5a..fce8bc8afeb7 100644 --- a/net/can/j1939/socket.c +++ b/net/can/j1939/socket.c @@ -398,6 +398,9 @@ static int j1939_sk_init(struct sock *sk) atomic_set(&jsk->skb_pending, 0); spin_lock_init(&jsk->sk_session_queue_lock); INIT_LIST_HEAD(&jsk->sk_session_queue); + + /* j1939_sk_sock_destruct() depends on SOCK_RCU_FREE flag */ + sock_set_flag(sk, SOCK_RCU_FREE); sk->sk_destruct = j1939_sk_sock_destruct; sk->sk_protocol = CAN_J1939; From ab4a0b8fcb9a95c02909b62049811bd2e586aaa4 Mon Sep 17 00:00:00 2001 From: Pavel Skripkin Date: Thu, 17 Jun 2021 21:51:30 +0300 Subject: [PATCH 5/5] net: can: ems_usb: fix use-after-free in ems_usb_disconnect() In ems_usb_disconnect() dev pointer, which is netdev private data, is used after free_candev() call: | if (dev) { | unregister_netdev(dev->netdev); | free_candev(dev->netdev); | | unlink_all_urbs(dev); | | usb_free_urb(dev->intr_urb); | | kfree(dev->intr_in_buffer); | kfree(dev->tx_msg_buffer); | } Fix it by simply moving free_candev() at the end of the block. Fail log: | BUG: KASAN: use-after-free in ems_usb_disconnect | Read of size 8 at addr ffff88804e041008 by task kworker/1:2/2895 | | CPU: 1 PID: 2895 Comm: kworker/1:2 Not tainted 5.13.0-rc5+ #164 | Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a-rebuilt.opensuse.4 | Workqueue: usb_hub_wq hub_event | Call Trace: | dump_stack (lib/dump_stack.c:122) | print_address_description.constprop.0.cold (mm/kasan/report.c:234) | kasan_report.cold (mm/kasan/report.c:420 mm/kasan/report.c:436) | ems_usb_disconnect (drivers/net/can/usb/ems_usb.c:683 drivers/net/can/usb/ems_usb.c:1058) Fixes: 702171adeed3 ("ems_usb: Added support for EMS CPC-USB/ARM7 CAN/USB interface") Link: https://lore.kernel.org/r/20210617185130.5834-1-paskripkin@gmail.com Cc: linux-stable Signed-off-by: Pavel Skripkin Signed-off-by: Marc Kleine-Budde --- drivers/net/can/usb/ems_usb.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/can/usb/ems_usb.c b/drivers/net/can/usb/ems_usb.c index 5af69787d9d5..0a37af4a3fa4 100644 --- a/drivers/net/can/usb/ems_usb.c +++ b/drivers/net/can/usb/ems_usb.c @@ -1053,7 +1053,6 @@ static void ems_usb_disconnect(struct usb_interface *intf) if (dev) { unregister_netdev(dev->netdev); - free_candev(dev->netdev); unlink_all_urbs(dev); @@ -1061,6 +1060,8 @@ static void ems_usb_disconnect(struct usb_interface *intf) kfree(dev->intr_in_buffer); kfree(dev->tx_msg_buffer); + + free_candev(dev->netdev); } }