[PATCH 5.4 086/152] io_uring: fix 32-bit compatability with sendmsg/recvmsg

[Greg Kroah-Hartman]

From: Jens Axboe <axboe@xxxxxxxxx>

commit d876836204897b6d7d911f942084f69a1e9d5c4d upstream.

We must set MSG_CMSG_COMPAT if we're in compatability mode, otherwise
the iovec import for these commands will not do the right thing and fail
the command with -EINVAL.

Found by running the test suite compiled as 32-bit.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: aa1fa28fc73e ("io_uring: add support for recvmsg()")
Fixes: 0fa03c624d8f ("io_uring: add support for sendmsg()")
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/io_uring.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1657,6 +1657,11 @@ static int io_send_recvmsg(struct io_kio
 		else if (force_nonblock)
 			flags |= MSG_DONTWAIT;
 
+#ifdef CONFIG_COMPAT
+		if (req->ctx->compat)
+			flags |= MSG_CMSG_COMPAT;
+#endif
+
 		msg = (struct user_msghdr __user *) (unsigned long)
 			READ_ONCE(sqe->addr);