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,