From: Xin Long lucien.xin@gmail.com
commit cc19862ffe454a5b632ca202e5a51bfec9f89fd2 upstream.
syzbot reported an use-after-free crash:
BUG: KASAN: use-after-free in tipc_recvmsg+0xf77/0xf90 net/tipc/socket.c:1979 Call Trace: tipc_recvmsg+0xf77/0xf90 net/tipc/socket.c:1979 sock_recvmsg_nosec net/socket.c:943 [inline] sock_recvmsg net/socket.c:961 [inline] sock_recvmsg+0xca/0x110 net/socket.c:957 tipc_conn_rcv_from_sock+0x162/0x2f0 net/tipc/topsrv.c:398 tipc_conn_recv_work+0xeb/0x190 net/tipc/topsrv.c:421 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
As Hoang pointed out, it was caused by skb_cb->bytes_read still accessed after calling tsk_advance_rx_queue() to free the skb in tipc_recvmsg().
This patch is to fix it by accessing skb_cb->bytes_read earlier than calling tsk_advance_rx_queue().
Fixes: f4919ff59c28 ("tipc: keep the skb in rcv queue until the whole data is read") Reported-by: syzbot+e6741b97d5552f97c24d@syzkaller.appspotmail.com Signed-off-by: Xin Long lucien.xin@gmail.com Acked-by: Jon Maloy jmaloy@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/tipc/socket.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
--- a/net/tipc/socket.c +++ b/net/tipc/socket.c @@ -1849,10 +1849,12 @@ static int tipc_recvmsg(struct socket *s tipc_node_distr_xmit(sock_net(sk), &xmitq); }
- if (!skb_cb->bytes_read) - tsk_advance_rx_queue(sk); + if (skb_cb->bytes_read) + goto exit; + + tsk_advance_rx_queue(sk);
- if (likely(!connected) || skb_cb->bytes_read) + if (likely(!connected)) goto exit;
/* Send connection flow control advertisement when applicable */