[PATCH io_uring-7.2 1/1] io_uring/zcrx: fail non-qops netdevs early

[Pavel Begunkov <asml.silence@gmail.com>]

netdev_get_by_index_lock() might return a netdev that doesn't have qops
and also relies on rtnl. We're going to reject it later when opening a
queue, but netdev_queue_get_dma_dev() warns before that. Reject non-qops
netdevs earlier for now.

RTNL: assertion failed at ./include/net/netdev_lock.h (72)
WARNING: ./include/net/netdev_lock.h:72 at netdev_assert_locked_ops_compat
    include/net/netdev_lock.h:72 [inline]
WARNING: ./include/net/netdev_lock.h:72 at netdev_queue_get_dma_dev+0x52e/0x660
    net/core/netdev_queues.c:43,
RIP: 0010:netdev_assert_locked_ops_compat include/net/netdev_lock.h:72 [inline]
RIP: 0010:netdev_queue_get_dma_dev+0x53a/0x660 net/core/netdev_queues.c:43
Call Trace:
 <TASK>
 zcrx_register_netdev io_uring/zcrx.c:831 [inline]
 io_register_zcrx+0xe94/0x1d30 io_uring/zcrx.c:983
 __io_uring_register io_uring/register.c:942 [inline]
 __do_sys_io_uring_register+0x1193/0x1bc0 io_uring/register.c:1040
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Cc: stable@vger.kernel.org
Fixes: b6c5f9454ef34 ("io_uring/zcrx: call netdev_queue_get_dma_dev() under instance lock")
Reported-by: syzbot+a78926bdac2adb52dc0e@syzkaller.appspotmail.com
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/zcrx.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index f1464ea8ca64..add91d6d6e52 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -825,6 +825,10 @@ static int zcrx_register_netdev(struct io_zcrx_ifq *ifq,
 						reg->if_idx);
 	if (!ifq->netdev)
 		return -ENODEV;
+	if (!ifq->netdev->queue_mgmt_ops) {
+		ret = -EOPNOTSUPP;
+		goto netdev_put_unlock;
+	}
 
 	netdev_hold(ifq->netdev, &ifq->netdev_tracker, GFP_KERNEL);
 
-- 
2.54.0