4.20-stable review patch. If anyone has any objections, please let me know.
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From: Ying Xue ying.xue@windriver.com
commit a88289f4ddee4165d5f796bd99e09eec3133c16b upstream.
syzbot reported:
BUG: KMSAN: uninit-value in tipc_conn_rcv_sub+0x184/0x950 net/tipc/topsrv.c:373 CPU: 0 PID: 66 Comm: kworker/u4:4 Not tainted 4.17.0-rc3+ #88 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: tipc_rcv tipc_conn_recv_work Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x185/0x1d0 lib/dump_stack.c:113 kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067 __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:683 tipc_conn_rcv_sub+0x184/0x950 net/tipc/topsrv.c:373 tipc_conn_rcv_from_sock net/tipc/topsrv.c:409 [inline] tipc_conn_recv_work+0x3cd/0x560 net/tipc/topsrv.c:424 process_one_work+0x12c6/0x1f60 kernel/workqueue.c:2145 worker_thread+0x113c/0x24f0 kernel/workqueue.c:2279 kthread+0x539/0x720 kernel/kthread.c:239 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:412
Local variable description: ----s.i@tipc_conn_recv_work Variable was created at: tipc_conn_recv_work+0x65/0x560 net/tipc/topsrv.c:419 process_one_work+0x12c6/0x1f60 kernel/workqueue.c:2145
In tipc_conn_rcv_from_sock(), it always supposes the length of message received from sock_recvmsg() is not smaller than the size of struct tipc_subscr. However, this assumption is false. Especially when the length of received message is shorter than struct tipc_subscr size, we will end up touching uninitialized fields in tipc_conn_rcv_sub().
Reported-by: syzbot+8951a3065ee7fd6d6e23@syzkaller.appspotmail.com Reported-by: syzbot+75e6e042c5bbf691fc82@syzkaller.appspotmail.com Signed-off-by: Ying Xue ying.xue@windriver.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/tipc/topsrv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/tipc/topsrv.c +++ b/net/tipc/topsrv.c @@ -398,7 +398,7 @@ static int tipc_conn_rcv_from_sock(struc ret = sock_recvmsg(con->sock, &msg, MSG_DONTWAIT); if (ret == -EWOULDBLOCK) return -EWOULDBLOCK; - if (ret > 0) { + if (ret == sizeof(s)) { read_lock_bh(&sk->sk_callback_lock); ret = tipc_conn_rcv_sub(srv, con, &s); read_unlock_bh(&sk->sk_callback_lock);