This is a note to let you know that I've just added the patch titled
mptcp: fix UaF in listener shutdown
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mptcp-fix-uaf-in-listener-shutdown.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit fdbcabf2f037f213ff3023adc0e338402c6a3509
Author: Paolo Abeni <pabeni@xxxxxxxxxx>
Date: Thu Mar 23 18:49:02 2023 +0100
mptcp: fix UaF in listener shutdown
[ Upstream commit 0a3f4f1f9c27215e4ddcd312558342e57b93e518 ]
Backports notes: one simple conflict in net/mptcp/protocol.c with:
commit f8c9dfbd875b ("mptcp: add pm listener events")
Where one commit removes code in __mptcp_close_ssk() while the other
one adds one line at the same place. We can simply remove the whole
condition because this extra instruction is not present in v6.1.
As reported by Christoph after having refactored the passive
socket initialization, the mptcp listener shutdown path is prone
to an UaF issue.
BUG: KASAN: use-after-free in _raw_spin_lock_bh+0x73/0xe0
Write of size 4 at addr ffff88810cb23098 by task syz-executor731/1266
CPU: 1 PID: 1266 Comm: syz-executor731 Not tainted 6.2.0-rc59af4eaa31c1f6c00c8f1e448ed99a45c66340dd5 #6
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x6e/0x91
print_report+0x16a/0x46f
kasan_report+0xad/0x130
kasan_check_range+0x14a/0x1a0
_raw_spin_lock_bh+0x73/0xe0
subflow_error_report+0x6d/0x110
sk_error_report+0x3b/0x190
tcp_disconnect+0x138c/0x1aa0
inet_child_forget+0x6f/0x2e0
inet_csk_listen_stop+0x209/0x1060
__mptcp_close_ssk+0x52d/0x610
mptcp_destroy_common+0x165/0x640
mptcp_destroy+0x13/0x80
__mptcp_destroy_sock+0xe7/0x270
__mptcp_close+0x70e/0x9b0
mptcp_close+0x2b/0x150
inet_release+0xe9/0x1f0
__sock_release+0xd2/0x280
sock_close+0x15/0x20
__fput+0x252/0xa20
task_work_run+0x169/0x250
exit_to_user_mode_prepare+0x113/0x120
syscall_exit_to_user_mode+0x1d/0x40
do_syscall_64+0x48/0x90
entry_SYSCALL_64_after_hwframe+0x72/0xdc
The msk grace period can legitly expire in between the last
reference count dropped in mptcp_subflow_queue_clean() and
the later eventual access in inet_csk_listen_stop()
After the previous patch we don't need anymore special-casing
msk listener socket cleanup: the mptcp worker will process each
of the unaccepted msk sockets.
Just drop the now unnecessary code.
Please note this commit depends on the two parent ones:
mptcp: refactor passive socket initialization
mptcp: use the workqueue to destroy unaccepted sockets
Fixes: 6aeed9045071 ("mptcp: fix race on unaccepted mptcp sockets")
Cc: stable@xxxxxxxxxxxxxxx
Reported-and-tested-by: Christoph Paasch <cpaasch@xxxxxxxxx>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/346
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Reviewed-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx>
Signed-off-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx>
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index b679e8a430a83..f0cde2d7233dc 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2380,11 +2380,6 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
mptcp_subflow_drop_ctx(ssk);
} else {
/* otherwise tcp will dispose of the ssk and subflow ctx */
- if (ssk->sk_state == TCP_LISTEN) {
- tcp_set_state(ssk, TCP_CLOSE);
- mptcp_subflow_queue_clean(sk, ssk);
- inet_csk_listen_stop(ssk);
- }
__tcp_close(ssk, 0);
/* close acquired an extra ref */
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 2cddd5b52e8fa..051e8022d6611 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -615,7 +615,6 @@ void mptcp_close_ssk(struct sock *sk, struct sock *ssk,
struct mptcp_subflow_context *subflow);
void __mptcp_subflow_send_ack(struct sock *ssk);
void mptcp_subflow_reset(struct sock *ssk);
-void mptcp_subflow_queue_clean(struct sock *sk, struct sock *ssk);
void mptcp_sock_graft(struct sock *sk, struct socket *parent);
struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk);
bool __mptcp_close(struct sock *sk, long timeout);
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 459621a0410cd..fc876c2480029 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1764,78 +1764,6 @@ static void subflow_state_change(struct sock *sk)
}
}
-void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk)
-{
- struct request_sock_queue *queue = &inet_csk(listener_ssk)->icsk_accept_queue;
- struct mptcp_sock *msk, *next, *head = NULL;
- struct request_sock *req;
-
- /* build a list of all unaccepted mptcp sockets */
- spin_lock_bh(&queue->rskq_lock);
- for (req = queue->rskq_accept_head; req; req = req->dl_next) {
- struct mptcp_subflow_context *subflow;
- struct sock *ssk = req->sk;
- struct mptcp_sock *msk;
-
- if (!sk_is_mptcp(ssk))
- continue;
-
- subflow = mptcp_subflow_ctx(ssk);
- if (!subflow || !subflow->conn)
- continue;
-
- /* skip if already in list */
- msk = mptcp_sk(subflow->conn);
- if (msk->dl_next || msk == head)
- continue;
-
- msk->dl_next = head;
- head = msk;
- }
- spin_unlock_bh(&queue->rskq_lock);
- if (!head)
- return;
-
- /* can't acquire the msk socket lock under the subflow one,
- * or will cause ABBA deadlock
- */
- release_sock(listener_ssk);
-
- for (msk = head; msk; msk = next) {
- struct sock *sk = (struct sock *)msk;
- bool do_cancel_work;
-
- lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
- next = msk->dl_next;
- msk->first = NULL;
- msk->dl_next = NULL;
-
- do_cancel_work = __mptcp_close(sk, 0);
- release_sock(sk);
- if (do_cancel_work) {
- /* lockdep will report a false positive ABBA deadlock
- * between cancel_work_sync and the listener socket.
- * The involved locks belong to different sockets WRT
- * the existing AB chain.
- * Using a per socket key is problematic as key
- * deregistration requires process context and must be
- * performed at socket disposal time, in atomic
- * context.
- * Just tell lockdep to consider the listener socket
- * released here.
- */
- mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_);
- mptcp_cancel_work(sk);
- mutex_acquire(&listener_sk->sk_lock.dep_map,
- SINGLE_DEPTH_NESTING, 0, _RET_IP_);
- }
- sock_put(sk);
- }
-
- /* we are still under the listener msk socket lock */
- lock_sock_nested(listener_ssk, SINGLE_DEPTH_NESTING);
-}
-
static int subflow_ulp_init(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
