FAILED: patch "[PATCH] io_uring: fix 32-bit compatability with sendmsg/recvmsg" failed to apply to 5.5-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.5-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From d876836204897b6d7d911f942084f69a1e9d5c4d Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Thu, 27 Feb 2020 14:17:49 -0700
Subject: [PATCH] io_uring: fix 32-bit compatability with sendmsg/recvmsg

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@vger.kernel.org
Fixes: aa1fa28fc73e ("io_uring: add support for recvmsg()")
Fixes: 0fa03c624d8f ("io_uring: add support for sendmsg()")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 05eea06f5421..6a595c13e108 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3001,6 +3001,11 @@ static int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	sr->msg = u64_to_user_ptr(READ_ONCE(sqe->addr));
 	sr->len = READ_ONCE(sqe->len);
 
+#ifdef CONFIG_COMPAT
+	if (req->ctx->compat)
+		sr->msg_flags |= MSG_CMSG_COMPAT;
+#endif
+
 	if (!io || req->opcode == IORING_OP_SEND)
 		return 0;
 	/* iovec is already imported */
@@ -3153,6 +3158,11 @@ static int io_recvmsg_prep(struct io_kiocb *req,
 	sr->msg = u64_to_user_ptr(READ_ONCE(sqe->addr));
 	sr->len = READ_ONCE(sqe->len);
 
+#ifdef CONFIG_COMPAT
+	if (req->ctx->compat)
+		sr->msg_flags |= MSG_CMSG_COMPAT;
+#endif
+
 	if (!io || req->opcode == IORING_OP_RECV)
 		return 0;
 	/* iovec is already imported */