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tipc: set con sock in tipc_conn_alloc 

A crash was reported by Wei Chen:

  BUG: kernel NULL pointer dereference, address: 0000000000000018
  RIP: 0010:tipc_conn_close+0x12/0x100
  Call Trace:
   tipc_topsrv_exit_net+0x139/0x320
   ops_exit_list.isra.9+0x49/0x80
   cleanup_net+0x31a/0x540
   process_one_work+0x3fa/0x9f0
   worker_thread+0x42/0x5c0

It was caused by !con->sock in tipc_conn_close(). In tipc_topsrv_accept(),
con is allocated in conn_idr then its sock is set:

  con = tipc_conn_alloc();
  ...                    <----[1]
  con->sock = newsock;

If tipc_conn_close() is called in anytime of [1], the null-pointer-def
is triggered by con->sock->sk due to con->sock is not yet set.

This patch fixes it by moving the con->sock setting to tipc_conn_alloc()
under s->idr_lock. So that con->sock can never be NULL when getting the
con from s->conn_idr. It will be also safer to move con->server and flag
CF_CONNECTED setting under s->idr_lock, as they should all be set before
tipc_conn_alloc() is called.

Fixes: c5fa7b3cf3 ("tipc: introduce new TIPC server infrastructure")
Reported-by: Wei Chen <harperchen1110@gmail.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Xin Long 2022-11-18 16:45:00 -05:00 committed by Jakub Kicinski
parent 1f0dd412e3
commit 0e5d56c64a
1 changed files with 5 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
net/tipc/topsrv.c
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@ -176,7 +176,7 @@ static void tipc_conn_close(struct tipc_conn *con)
conn_put(con);
}
static struct tipc_conn *tipc_conn_alloc(struct tipc_topsrv *s)
static struct tipc_conn *tipc_conn_alloc(struct tipc_topsrv *s, struct socket *sock)
{
struct tipc_conn *con;
int ret;
@ -202,10 +202,11 @@ static struct tipc_conn *tipc_conn_alloc(struct tipc_topsrv *s)
}
con->conid = ret;
s->idr_in_use++;
spin_unlock_bh(&s->idr_lock);
set_bit(CF_CONNECTED, &con->flags);
con->server = s;
con->sock = sock;
spin_unlock_bh(&s->idr_lock);
return con;
}
@ -467,7 +468,7 @@ static void tipc_topsrv_accept(struct work_struct *work)
ret = kernel_accept(lsock, &newsock, O_NONBLOCK);
if (ret < 0)
return;
con = tipc_conn_alloc(srv);
con = tipc_conn_alloc(srv, newsock);
if (IS_ERR(con)) {
ret = PTR_ERR(con);
sock_release(newsock);
@ -479,7 +480,6 @@ static void tipc_topsrv_accept(struct work_struct *work)
newsk->sk_data_ready = tipc_conn_data_ready;
newsk->sk_write_space = tipc_conn_write_space;
newsk->sk_user_data = con;
con->sock = newsock;
write_unlock_bh(&newsk->sk_callback_lock);
/* Wake up receive process in case of 'SYN+' message */
@ -577,12 +577,11 @@ bool tipc_topsrv_kern_subscr(struct net *net, u32 port, u32 type, u32 lower,
sub.filter = filter;
*(u64 *)&sub.usr_handle = (u64)port;
con = tipc_conn_alloc(tipc_topsrv(net));
con = tipc_conn_alloc(tipc_topsrv(net), NULL);
if (IS_ERR(con))
return false;
*conid = con->conid;
con->sock = NULL;
rc = tipc_conn_rcv_sub(tipc_topsrv(net), con, &sub);
if (rc >= 0)
return true;