diff options
| author | Xin Long <lucien.xin@gmail.com> | 2022-10-18 15:19:50 -0400 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-10-20 21:08:17 -0700 |
| commit | 82cb4e4612c633a9ce320e1773114875604a3cce (patch) | |
| tree | 87d62fabf41bb68b4e46eac9504bdad680ad0672 /net/tipc | |
| parent | 6d36c728bc2e2d632f4b0dea00df5532e20dfdab (diff) | |
tipc: fix a null-ptr-deref in tipc_topsrv_accept
syzbot found a crash in tipc_topsrv_accept:
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
Workqueue: tipc_rcv tipc_topsrv_accept
RIP: 0010:kernel_accept+0x22d/0x350 net/socket.c:3487
Call Trace:
<TASK>
tipc_topsrv_accept+0x197/0x280 net/tipc/topsrv.c:460
process_one_work+0x991/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e4/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
It was caused by srv->listener that might be set to null by
tipc_topsrv_stop() in net .exit whereas it's still used in
tipc_topsrv_accept() worker.
srv->listener is protected by srv->idr_lock in tipc_topsrv_stop(), so add
a check for srv->listener under srv->idr_lock in tipc_topsrv_accept() to
avoid the null-ptr-deref. To ensure the lsock is not released during the
tipc_topsrv_accept(), move sock_release() after tipc_topsrv_work_stop()
where it's waiting until the tipc_topsrv_accept worker to be done.
Note that sk_callback_lock is used to protect sk->sk_user_data instead of
srv->listener, and it should check srv in tipc_topsrv_listener_data_ready()
instead. This also ensures that no more tipc_topsrv_accept worker will be
started after tipc_conn_close() is called in tipc_topsrv_stop() where it
sets sk->sk_user_data to null.
Fixes: 0ef897be12b8 ("tipc: separate topology server listener socket from subcsriber sockets")
Reported-by: syzbot+c5ce866a8d30f4be0651@syzkaller.appspotmail.com
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Jon Maloy <jmaloy@redhat.com>
Link: https://lore.kernel.org/r/4eee264380c409c61c6451af1059b7fb271a7e7b.1666120790.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/tipc')
| -rw-r--r-- | net/tipc/topsrv.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/net/tipc/topsrv.c b/net/tipc/topsrv.c index 14fd05fd6107..d92ec92f0b71 100644 --- a/net/tipc/topsrv.c +++ b/net/tipc/topsrv.c @@ -450,12 +450,19 @@ static void tipc_conn_data_ready(struct sock *sk) static void tipc_topsrv_accept(struct work_struct *work) { struct tipc_topsrv *srv = container_of(work, struct tipc_topsrv, awork); - struct socket *lsock = srv->listener; - struct socket *newsock; + struct socket *newsock, *lsock; struct tipc_conn *con; struct sock *newsk; int ret; + spin_lock_bh(&srv->idr_lock); + if (!srv->listener) { + spin_unlock_bh(&srv->idr_lock); + return; + } + lsock = srv->listener; + spin_unlock_bh(&srv->idr_lock); + while (1) { ret = kernel_accept(lsock, &newsock, O_NONBLOCK); if (ret < 0) @@ -489,7 +496,7 @@ static void tipc_topsrv_listener_data_ready(struct sock *sk) read_lock_bh(&sk->sk_callback_lock); srv = sk->sk_user_data; - if (srv->listener) + if (srv) queue_work(srv->rcv_wq, &srv->awork); read_unlock_bh(&sk->sk_callback_lock); } @@ -699,8 +706,9 @@ static void tipc_topsrv_stop(struct net *net) __module_get(lsock->sk->sk_prot_creator->owner); srv->listener = NULL; spin_unlock_bh(&srv->idr_lock); - sock_release(lsock); + tipc_topsrv_work_stop(srv); + sock_release(lsock); idr_destroy(&srv->conn_idr); kfree(srv); } |