diff mbox series

[net,1/3] can: j1939: prevent deadlock by changing j1939_socks_lock to rwlock

Message ID 20240214140348.2412776-2-mkl@pengutronix.de (mailing list archive)
State Accepted
Commit 6cdedc18ba7b9dacc36466e27e3267d201948c8d
Delegated to: Netdev Maintainers
Headers show
Series [net,1/3] can: j1939: prevent deadlock by changing j1939_socks_lock to rwlock | expand

Checks

Context Check Description
netdev/series_format success Pull request is its own cover letter
netdev/tree_selection success Clearly marked for net
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 977 this patch: 977
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 4 maintainers not CCed: pabeni@redhat.com robin@protonic.nl socketcan@hartkopp.net edumazet@google.com
netdev/build_clang success Errors and warnings before: 993 this patch: 993
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 994 this patch: 994
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 94 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Marc Kleine-Budde Feb. 14, 2024, 1:59 p.m. UTC 
From: Ziqi Zhao <astrajoan@yahoo.com>

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: <syzbot+1591462f226d9cbf0564@syzkaller.appspotmail.com>
Signed-off-by: Ziqi Zhao <astrajoan@yahoo.com>
Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
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 <mkl@pengutronix.de>
---
 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(-)


base-commit: 858b31133dbec88465bcc0a006f4dc43173662b8

Comments

Paolo Abeni Feb. 15, 2024, 11:43 a.m. UTC | #1 
On Wed, 2024-02-14 at 14:59 +0100, Marc Kleine-Budde wrote:
> From: Ziqi Zhao <astrajoan@yahoo.com>
> 
> 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.

Just FYI, Eric recently did a great job removing most rwlock in
networking code, see commit 0daf07e52709 ("raw: convert raw sockets to
RCU").

I'm unsure if the same reasoning apply to can, but perhaps you could
consider converting this code to RCU for net-next.

Cheers,

Paolo
patchwork-bot+netdevbpf@kernel.org Feb. 15, 2024, 11:50 a.m. UTC | #2 
Hello:

This series was applied to netdev/net.git (main)
by Marc Kleine-Budde <mkl@pengutronix.de>:

On Wed, 14 Feb 2024 14:59:05 +0100 you wrote:
> From: Ziqi Zhao <astrajoan@yahoo.com>
> 
> 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
> 
> [...]

Here is the summary with links:
  - [net,1/3] can: j1939: prevent deadlock by changing j1939_socks_lock to rwlock
    https://git.kernel.org/netdev/net/c/6cdedc18ba7b
  - [net,2/3] can: j1939: Fix UAF in j1939_sk_match_filter during setsockopt(SO_J1939_FILTER)
    https://git.kernel.org/netdev/net/c/efe7cf828039
  - [net,3/3] can: netlink: Fix TDCO calculation using the old data bittiming
    https://git.kernel.org/netdev/net/c/2aa0a5e65eae

You are awesome, thank you!
diff mbox series

Patch

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,