Subject: FAILED: patch "[PATCH] io_uring: fix double prep iovec leak" failed to apply to 5.5-stable tree
To:     asml.silence@gmail.com, axboe@kernel.dk
Cc:     <stable@vger.kernel.org>
From:   <gregkh@linuxfoundation.org>
Date:   Mon, 17 Feb 2020 15:04:49 +0100
Message-ID: <158194828922495@kroah.com>
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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 5f798beaf35d79355cbf18019c1993a84475a2c3 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Sat, 8 Feb 2020 13:28:02 +0300
Subject: [PATCH] io_uring: fix double prep iovec leak

Requests may be prepared multiple times with ->io allocated (i.e. async
prepared). Preparation functions don't handle it and forget about
previously allocated resources. This may happen in case of:
- spurious defer_check
- non-head (i.e. async prepared) request executed in sync (via nxt).

Make the handlers check, whether they already allocated resources, which
is true IFF REQ_F_NEED_CLEANUP is set.

Cc: stable@vger.kernel.org # 5.5
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 759301bdb19b..097701782339 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2205,7 +2205,8 @@ static int io_read_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 	if (unlikely(!(req->file->f_mode & FMODE_READ)))
 		return -EBADF;
 
-	if (!req->io)
+	/* either don't need iovec imported or already have it */
+	if (!req->io || req->flags & REQ_F_NEED_CLEANUP)
 		return 0;
 
 	io = req->io;
@@ -2293,7 +2294,8 @@ static int io_write_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 	if (unlikely(!(req->file->f_mode & FMODE_WRITE)))
 		return -EBADF;
 
-	if (!req->io)
+	/* either don't need iovec imported or already have it */
+	if (!req->io || req->flags & REQ_F_NEED_CLEANUP)
 		return 0;
 
 	io = req->io;
@@ -2993,6 +2995,9 @@ static int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 
 	if (!io || req->opcode == IORING_OP_SEND)
 		return 0;
+	/* iovec is already imported */
+	if (req->flags & REQ_F_NEED_CLEANUP)
+		return 0;
 
 	io->msg.iov = io->msg.fast_iov;
 	ret = sendmsg_copy_msghdr(&io->msg.msg, sr->msg, sr->msg_flags,
@@ -3143,6 +3148,9 @@ static int io_recvmsg_prep(struct io_kiocb *req,
 
 	if (!io || req->opcode == IORING_OP_RECV)
 		return 0;
+	/* iovec is already imported */
+	if (req->flags & REQ_F_NEED_CLEANUP)
+		return 0;
 
 	io->msg.iov = io->msg.fast_iov;
 	ret = recvmsg_copy_msghdr(&io->msg.msg, sr->msg, sr->msg_flags,