From: Xin Long lucien.xin@gmail.com
[ Upstream commit a7b42969d63f47320853a802efd879fbdc4e010e ]
One extra conn_get() is needed in tipc_conn_alloc(), as after tipc_conn_alloc() is called, tipc_conn_close() may free this con before deferencing it in tipc_topsrv_accept():
tipc_conn_alloc(); newsk = newsock->sk; <---- tipc_conn_close(); write_lock_bh(&sk->sk_callback_lock); newsk->sk_data_ready = tipc_conn_data_ready;
Then an uaf issue can be triggered:
BUG: KASAN: use-after-free in tipc_topsrv_accept+0x1e7/0x370 [tipc] Call Trace: <TASK> dump_stack_lvl+0x33/0x46 print_report+0x178/0x4b0 kasan_report+0x8c/0x100 kasan_check_range+0x179/0x1e0 tipc_topsrv_accept+0x1e7/0x370 [tipc] process_one_work+0x6a3/0x1030 worker_thread+0x8a/0xdf0
This patch fixes it by holding it in tipc_conn_alloc(), then after all accessing in tipc_topsrv_accept() releasing it. Note when does this in tipc_topsrv_kern_subscr(), as tipc_conn_rcv_sub() returns 0 or -1 only, we don't need to check for "> 0".
Fixes: c5fa7b3cf3cb ("tipc: introduce new TIPC server infrastructure") Signed-off-by: Xin Long lucien.xin@gmail.com Acked-by: Jon Maloy jmaloy@redhat.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/tipc/topsrv.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/net/tipc/topsrv.c b/net/tipc/topsrv.c index 532343c7788a..88e8e8d69b60 100644 --- a/net/tipc/topsrv.c +++ b/net/tipc/topsrv.c @@ -207,6 +207,7 @@ static struct tipc_conn *tipc_conn_alloc(struct tipc_topsrv *s, struct socket *s set_bit(CF_CONNECTED, &con->flags); con->server = s; con->sock = sock; + conn_get(con); spin_unlock_bh(&s->idr_lock);
return con; @@ -484,6 +485,7 @@ static void tipc_topsrv_accept(struct work_struct *work)
/* Wake up receive process in case of 'SYN+' message */ newsk->sk_data_ready(newsk); + conn_put(con); } }
@@ -583,10 +585,11 @@ bool tipc_topsrv_kern_subscr(struct net *net, u32 port, u32 type, u32 lower,
*conid = con->conid; rc = tipc_conn_rcv_sub(tipc_topsrv(net), con, &sub); - if (rc >= 0) - return true; + if (rc) + conn_put(con); + conn_put(con); - return false; + return !rc; }
void tipc_topsrv_kern_unsubscr(struct net *net, int conid)