From 6cdedc18ba7b9dacc36466e27e3267d201948c8d Mon Sep 17 00:00:00 2001 From: Ziqi Zhao Date: Fri, 21 Jul 2023 09:22:26 -0700 Subject: can: j1939: prevent deadlock by changing j1939_socks_lock to rwlock The following 3 locks would race against each other, causing the deadlock situation in the Syzbot bug report: - j1939_socks_lock - active_session_list_lock - sk_session_queue_lock A reasonable fix is to change j1939_socks_lock to an rwlock, since in the rare situations where a write lock is required for the linked list that j1939_socks_lock is protecting, the code does not attempt to acquire any more locks. This would break the circular lock dependency, where, for example, the current thread already locks j1939_socks_lock and attempts to acquire sk_session_queue_lock, and at the same time, another thread attempts to acquire j1939_socks_lock while holding sk_session_queue_lock. NOTE: This patch along does not fix the unregister_netdevice bug reported by Syzbot; instead, it solves a deadlock situation to prepare for one or more further patches to actually fix the Syzbot bug, which appears to be a reference counting problem within the j1939 codebase. Reported-by: Signed-off-by: Ziqi Zhao Reviewed-by: Oleksij Rempel Acked-by: Oleksij Rempel Link: https://lore.kernel.org/all/20230721162226.8639-1-astrajoan@yahoo.com [mkl: remove unrelated newline change] Cc: stable@vger.kernel.org Signed-off-by: Marc Kleine-Budde --- net/can/j1939/j1939-priv.h | 2 +- net/can/j1939/main.c | 2 +- net/can/j1939/socket.c | 24 ++++++++++++------------ 3 files changed, 14 insertions(+), 14 deletions(-) (limited to 'net/can') diff --git a/net/can/j1939/j1939-priv.h b/net/can/j1939/j1939-priv.h index 16af1a7f80f6..74f15592d170 100644 --- a/net/can/j1939/j1939-priv.h +++ b/net/can/j1939/j1939-priv.h @@ -86,7 +86,7 @@ struct j1939_priv { unsigned int tp_max_packet_size; /* lock for j1939_socks list */ - spinlock_t j1939_socks_lock; + rwlock_t j1939_socks_lock; struct list_head j1939_socks; struct kref rx_kref; diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c index ecff1c947d68..a6fb89fa6278 100644 --- a/net/can/j1939/main.c +++ b/net/can/j1939/main.c @@ -274,7 +274,7 @@ struct j1939_priv *j1939_netdev_start(struct net_device *ndev) return ERR_PTR(-ENOMEM); j1939_tp_init(priv); - spin_lock_init(&priv->j1939_socks_lock); + rwlock_init(&priv->j1939_socks_lock); INIT_LIST_HEAD(&priv->j1939_socks); mutex_lock(&j1939_netdev_lock); diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c index 14c431663233..94cfc2315e54 100644 --- a/net/can/j1939/socket.c +++ b/net/can/j1939/socket.c @@ -80,16 +80,16 @@ static void j1939_jsk_add(struct j1939_priv *priv, struct j1939_sock *jsk) jsk->state |= J1939_SOCK_BOUND; j1939_priv_get(priv); - spin_lock_bh(&priv->j1939_socks_lock); + write_lock_bh(&priv->j1939_socks_lock); list_add_tail(&jsk->list, &priv->j1939_socks); - spin_unlock_bh(&priv->j1939_socks_lock); + write_unlock_bh(&priv->j1939_socks_lock); } static void j1939_jsk_del(struct j1939_priv *priv, struct j1939_sock *jsk) { - spin_lock_bh(&priv->j1939_socks_lock); + write_lock_bh(&priv->j1939_socks_lock); list_del_init(&jsk->list); - spin_unlock_bh(&priv->j1939_socks_lock); + write_unlock_bh(&priv->j1939_socks_lock); j1939_priv_put(priv); jsk->state &= ~J1939_SOCK_BOUND; @@ -329,13 +329,13 @@ bool j1939_sk_recv_match(struct j1939_priv *priv, struct j1939_sk_buff_cb *skcb) struct j1939_sock *jsk; bool match = false; - spin_lock_bh(&priv->j1939_socks_lock); + read_lock_bh(&priv->j1939_socks_lock); list_for_each_entry(jsk, &priv->j1939_socks, list) { match = j1939_sk_recv_match_one(jsk, skcb); if (match) break; } - spin_unlock_bh(&priv->j1939_socks_lock); + read_unlock_bh(&priv->j1939_socks_lock); return match; } @@ -344,11 +344,11 @@ void j1939_sk_recv(struct j1939_priv *priv, struct sk_buff *skb) { struct j1939_sock *jsk; - spin_lock_bh(&priv->j1939_socks_lock); + read_lock_bh(&priv->j1939_socks_lock); list_for_each_entry(jsk, &priv->j1939_socks, list) { j1939_sk_recv_one(jsk, skb); } - spin_unlock_bh(&priv->j1939_socks_lock); + read_unlock_bh(&priv->j1939_socks_lock); } static void j1939_sk_sock_destruct(struct sock *sk) @@ -1080,12 +1080,12 @@ void j1939_sk_errqueue(struct j1939_session *session, } /* spread RX notifications to all sockets subscribed to this session */ - spin_lock_bh(&priv->j1939_socks_lock); + read_lock_bh(&priv->j1939_socks_lock); list_for_each_entry(jsk, &priv->j1939_socks, list) { if (j1939_sk_recv_match_one(jsk, &session->skcb)) __j1939_sk_errqueue(session, &jsk->sk, type); } - spin_unlock_bh(&priv->j1939_socks_lock); + read_unlock_bh(&priv->j1939_socks_lock); }; void j1939_sk_send_loop_abort(struct sock *sk, int err) @@ -1273,7 +1273,7 @@ void j1939_sk_netdev_event_netdown(struct j1939_priv *priv) struct j1939_sock *jsk; int error_code = ENETDOWN; - spin_lock_bh(&priv->j1939_socks_lock); + read_lock_bh(&priv->j1939_socks_lock); list_for_each_entry(jsk, &priv->j1939_socks, list) { jsk->sk.sk_err = error_code; if (!sock_flag(&jsk->sk, SOCK_DEAD)) @@ -1281,7 +1281,7 @@ void j1939_sk_netdev_event_netdown(struct j1939_priv *priv) j1939_sk_queue_drop_all(priv, jsk, error_code); } - spin_unlock_bh(&priv->j1939_socks_lock); + read_unlock_bh(&priv->j1939_socks_lock); } static int j1939_sk_no_ioctlcmd(struct socket *sock, unsigned int cmd, -- cgit v1.2.3 From efe7cf828039aedb297c1f9920b638fffee6aabc Mon Sep 17 00:00:00 2001 From: Oleksij Rempel Date: Fri, 20 Oct 2023 15:38:14 +0200 Subject: can: j1939: Fix UAF in j1939_sk_match_filter during setsockopt(SO_J1939_FILTER) Lock jsk->sk to prevent UAF when setsockopt(..., SO_J1939_FILTER, ...) modifies jsk->filters while receiving packets. Following trace was seen on affected system: ================================================================== BUG: KASAN: slab-use-after-free in j1939_sk_recv_match_one+0x1af/0x2d0 [can_j1939] Read of size 4 at addr ffff888012144014 by task j1939/350 CPU: 0 PID: 350 Comm: j1939 Tainted: G W OE 6.5.0-rc5 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Call Trace: print_report+0xd3/0x620 ? kasan_complete_mode_report_info+0x7d/0x200 ? j1939_sk_recv_match_one+0x1af/0x2d0 [can_j1939] kasan_report+0xc2/0x100 ? j1939_sk_recv_match_one+0x1af/0x2d0 [can_j1939] __asan_load4+0x84/0xb0 j1939_sk_recv_match_one+0x1af/0x2d0 [can_j1939] j1939_sk_recv+0x20b/0x320 [can_j1939] ? __kasan_check_write+0x18/0x20 ? __pfx_j1939_sk_recv+0x10/0x10 [can_j1939] ? j1939_simple_recv+0x69/0x280 [can_j1939] ? j1939_ac_recv+0x5e/0x310 [can_j1939] j1939_can_recv+0x43f/0x580 [can_j1939] ? __pfx_j1939_can_recv+0x10/0x10 [can_j1939] ? raw_rcv+0x42/0x3c0 [can_raw] ? __pfx_j1939_can_recv+0x10/0x10 [can_j1939] can_rcv_filter+0x11f/0x350 [can] can_receive+0x12f/0x190 [can] ? __pfx_can_rcv+0x10/0x10 [can] can_rcv+0xdd/0x130 [can] ? __pfx_can_rcv+0x10/0x10 [can] __netif_receive_skb_one_core+0x13d/0x150 ? __pfx___netif_receive_skb_one_core+0x10/0x10 ? __kasan_check_write+0x18/0x20 ? _raw_spin_lock_irq+0x8c/0xe0 __netif_receive_skb+0x23/0xb0 process_backlog+0x107/0x260 __napi_poll+0x69/0x310 net_rx_action+0x2a1/0x580 ? __pfx_net_rx_action+0x10/0x10 ? __pfx__raw_spin_lock+0x10/0x10 ? handle_irq_event+0x7d/0xa0 __do_softirq+0xf3/0x3f8 do_softirq+0x53/0x80 __local_bh_enable_ip+0x6e/0x70 netif_rx+0x16b/0x180 can_send+0x32b/0x520 [can] ? __pfx_can_send+0x10/0x10 [can] ? __check_object_size+0x299/0x410 raw_sendmsg+0x572/0x6d0 [can_raw] ? __pfx_raw_sendmsg+0x10/0x10 [can_raw] ? apparmor_socket_sendmsg+0x2f/0x40 ? __pfx_raw_sendmsg+0x10/0x10 [can_raw] sock_sendmsg+0xef/0x100 sock_write_iter+0x162/0x220 ? __pfx_sock_write_iter+0x10/0x10 ? __rtnl_unlock+0x47/0x80 ? security_file_permission+0x54/0x320 vfs_write+0x6ba/0x750 ? __pfx_vfs_write+0x10/0x10 ? __fget_light+0x1ca/0x1f0 ? __rcu_read_unlock+0x5b/0x280 ksys_write+0x143/0x170 ? __pfx_ksys_write+0x10/0x10 ? __kasan_check_read+0x15/0x20 ? fpregs_assert_state_consistent+0x62/0x70 __x64_sys_write+0x47/0x60 do_syscall_64+0x60/0x90 ? do_syscall_64+0x6d/0x90 ? irqentry_exit+0x3f/0x50 ? exc_page_fault+0x79/0xf0 entry_SYSCALL_64_after_hwframe+0x6e/0xd8 Allocated by task 348: kasan_save_stack+0x2a/0x50 kasan_set_track+0x29/0x40 kasan_save_alloc_info+0x1f/0x30 __kasan_kmalloc+0xb5/0xc0 __kmalloc_node_track_caller+0x67/0x160 j1939_sk_setsockopt+0x284/0x450 [can_j1939] __sys_setsockopt+0x15c/0x2f0 __x64_sys_setsockopt+0x6b/0x80 do_syscall_64+0x60/0x90 entry_SYSCALL_64_after_hwframe+0x6e/0xd8 Freed by task 349: kasan_save_stack+0x2a/0x50 kasan_set_track+0x29/0x40 kasan_save_free_info+0x2f/0x50 __kasan_slab_free+0x12e/0x1c0 __kmem_cache_free+0x1b9/0x380 kfree+0x7a/0x120 j1939_sk_setsockopt+0x3b2/0x450 [can_j1939] __sys_setsockopt+0x15c/0x2f0 __x64_sys_setsockopt+0x6b/0x80 do_syscall_64+0x60/0x90 entry_SYSCALL_64_after_hwframe+0x6e/0xd8 Fixes: 9d71dd0c70099 ("can: add support of SAE J1939 protocol") Reported-by: Sili Luo Suggested-by: Sili Luo Acked-by: Oleksij Rempel Cc: stable@vger.kernel.org Signed-off-by: Oleksij Rempel Link: https://lore.kernel.org/all/20231020133814.383996-1-o.rempel@pengutronix.de Signed-off-by: Marc Kleine-Budde --- net/can/j1939/j1939-priv.h | 1 + net/can/j1939/socket.c | 22 ++++++++++++++++++---- 2 files changed, 19 insertions(+), 4 deletions(-) (limited to 'net/can') diff --git a/net/can/j1939/j1939-priv.h b/net/can/j1939/j1939-priv.h index 74f15592d170..31a93cae5111 100644 --- a/net/can/j1939/j1939-priv.h +++ b/net/can/j1939/j1939-priv.h @@ -301,6 +301,7 @@ struct j1939_sock { int ifindex; struct j1939_addr addr; + spinlock_t filters_lock; struct j1939_filter *filters; int nfilters; pgn_t pgn_rx_filter; diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c index 94cfc2315e54..305dd72c844c 100644 --- a/net/can/j1939/socket.c +++ b/net/can/j1939/socket.c @@ -262,12 +262,17 @@ static bool j1939_sk_match_dst(struct j1939_sock *jsk, static bool j1939_sk_match_filter(struct j1939_sock *jsk, const struct j1939_sk_buff_cb *skcb) { - const struct j1939_filter *f = jsk->filters; - int nfilter = jsk->nfilters; + const struct j1939_filter *f; + int nfilter; + + spin_lock_bh(&jsk->filters_lock); + + f = jsk->filters; + nfilter = jsk->nfilters; if (!nfilter) /* receive all when no filters are assigned */ - return true; + goto filter_match_found; for (; nfilter; ++f, --nfilter) { if ((skcb->addr.pgn & f->pgn_mask) != f->pgn) @@ -276,9 +281,15 @@ static bool j1939_sk_match_filter(struct j1939_sock *jsk, continue; if ((skcb->addr.src_name & f->name_mask) != f->name) continue; - return true; + goto filter_match_found; } + + spin_unlock_bh(&jsk->filters_lock); return false; + +filter_match_found: + spin_unlock_bh(&jsk->filters_lock); + return true; } static bool j1939_sk_recv_match_one(struct j1939_sock *jsk, @@ -401,6 +412,7 @@ 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); + spin_lock_init(&jsk->filters_lock); /* j1939_sk_sock_destruct() depends on SOCK_RCU_FREE flag */ sock_set_flag(sk, SOCK_RCU_FREE); @@ -703,9 +715,11 @@ static int j1939_sk_setsockopt(struct socket *sock, int level, int optname, } lock_sock(&jsk->sk); + spin_lock_bh(&jsk->filters_lock); ofilters = jsk->filters; jsk->filters = filters; jsk->nfilters = count; + spin_unlock_bh(&jsk->filters_lock); release_sock(&jsk->sk); kfree(ofilters); return 0; -- cgit v1.2.3