Re: [PATCH] io_uring: fix iovec leaks

From: Pavel Begunkov
Date: Fri Feb 07 2020 - 14:10:27 EST

On 07/02/2020 22:04, Pavel Begunkov wrote:
> Allocated iovec is freed only in io_{read,write,send,recv)(), and just
> leaves it if an error occured. There are plenty of such cases:
> - cancellation of non-head requests
> - fail grabbing files in __io_queue_sqe()
> - set REQ_F_NOWAIT and returning in __io_queue_sqe()
> - etc.
>
> Add REQ_F_NEED_CLEANUP, which will force such requests with custom
> allocated resourses go through cleanup handlers on put.

This is probably desirable in stable-5.5, so I tried to not change much.
I'll hide common parts in following patches for-5.6/next.

> Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
> ---
> fs/io_uring.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 49 insertions(+), 2 deletions(-)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 1914351ebd5e..d699695ef809 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -478,6 +478,7 @@ enum {
> REQ_F_MUST_PUNT_BIT,
> REQ_F_TIMEOUT_NOSEQ_BIT,
> REQ_F_COMP_LOCKED_BIT,
> + REQ_F_NEED_CLEANUP_BIT,
> };
>
> enum {
> @@ -516,6 +517,8 @@ enum {
> REQ_F_TIMEOUT_NOSEQ = BIT(REQ_F_TIMEOUT_NOSEQ_BIT),
> /* completion under lock */
> REQ_F_COMP_LOCKED = BIT(REQ_F_COMP_LOCKED_BIT),
> + /* needs cleanup */
> + REQ_F_NEED_CLEANUP = BIT(REQ_F_NEED_CLEANUP_BIT),
>
> };
>
> @@ -749,6 +752,7 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
> unsigned nr_args);
> static int io_grab_files(struct io_kiocb *req);
> static void io_ring_file_ref_flush(struct fixed_file_data *data);
> +static void io_cleanup_req(struct io_kiocb *req);
>
> static struct kmem_cache *req_cachep;
>
> @@ -1236,6 +1240,9 @@ static void __io_free_req(struct io_kiocb *req)
> {
> __io_req_aux_free(req);
>
> + if (req->flags & REQ_F_NEED_CLEANUP)
> + io_cleanup_req(req);
> +
> if (req->flags & REQ_F_INFLIGHT) {
> struct io_ring_ctx *ctx = req->ctx;
> unsigned long flags;
> @@ -2129,6 +2136,8 @@ static void io_req_map_rw(struct io_kiocb *req, ssize_t io_size,
> req->io->rw.iov = req->io->rw.fast_iov;
> memcpy(req->io->rw.iov, fast_iov,
> sizeof(struct iovec) * iter->nr_segs);
> + } else {
> + req->flags |= REQ_F_NEED_CLEANUP;
> }
> }
>
> @@ -2239,6 +2248,7 @@ static int io_read(struct io_kiocb *req, struct io_kiocb **nxt,
> }
> out_free:
> kfree(iovec);
> + req->flags &= ~REQ_F_NEED_CLEANUP;
> return ret;
> }
>
> @@ -2343,6 +2353,7 @@ static int io_write(struct io_kiocb *req, struct io_kiocb **nxt,
> }
> }
> out_free:
> + req->flags &= ~REQ_F_NEED_CLEANUP;
> kfree(iovec);
> return ret;
> }
> @@ -2943,6 +2954,7 @@ static int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
> #if defined(CONFIG_NET)
> struct io_sr_msg *sr = &req->sr_msg;
> struct io_async_ctx *io = req->io;
> + int ret;
>
> sr->msg_flags = READ_ONCE(sqe->msg_flags);
> sr->msg = u64_to_user_ptr(READ_ONCE(sqe->addr));
> @@ -2952,8 +2964,11 @@ static int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
> return 0;
>
> io->msg.iov = io->msg.fast_iov;
> - return sendmsg_copy_msghdr(&io->msg.msg, sr->msg, sr->msg_flags,
> + ret = sendmsg_copy_msghdr(&io->msg.msg, sr->msg, sr->msg_flags,
> &io->msg.iov);
> + if (!ret)
> + req->flags |= REQ_F_NEED_CLEANUP;
> + return ret;
> #else
> return -EOPNOTSUPP;
> #endif
> @@ -3011,6 +3026,7 @@ static int io_sendmsg(struct io_kiocb *req, struct io_kiocb **nxt,
> kfree(kmsg->iov);
> return -ENOMEM;
> }
> + req->flags |= REQ_F_NEED_CLEANUP;
> memcpy(&req->io->msg, &io.msg, sizeof(io.msg));
> return -EAGAIN;
> }
> @@ -3020,6 +3036,7 @@ static int io_sendmsg(struct io_kiocb *req, struct io_kiocb **nxt,
>
> if (kmsg && kmsg->iov != kmsg->fast_iov)
> kfree(kmsg->iov);
> + req->flags &= ~REQ_F_NEED_CLEANUP;
> io_cqring_add_event(req, ret);
> if (ret < 0)
> req_set_fail_links(req);
> @@ -3087,6 +3104,7 @@ static int io_recvmsg_prep(struct io_kiocb *req,
> #if defined(CONFIG_NET)
> struct io_sr_msg *sr = &req->sr_msg;
> struct io_async_ctx *io = req->io;
> + int ret;
>
> sr->msg_flags = READ_ONCE(sqe->msg_flags);
> sr->msg = u64_to_user_ptr(READ_ONCE(sqe->addr));
> @@ -3096,8 +3114,11 @@ static int io_recvmsg_prep(struct io_kiocb *req,
> return 0;
>
> io->msg.iov = io->msg.fast_iov;
> - return recvmsg_copy_msghdr(&io->msg.msg, sr->msg, sr->msg_flags,
> + ret = recvmsg_copy_msghdr(&io->msg.msg, sr->msg, sr->msg_flags,
> &io->msg.uaddr, &io->msg.iov);
> + if (!ret)
> + req->flags |= REQ_F_NEED_CLEANUP;
> + return ret;
> #else
> return -EOPNOTSUPP;
> #endif
> @@ -3158,6 +3179,7 @@ static int io_recvmsg(struct io_kiocb *req, struct io_kiocb **nxt,
> return -ENOMEM;
> }
> memcpy(&req->io->msg, &io.msg, sizeof(io.msg));
> + req->flags |= REQ_F_NEED_CLEANUP;
> return -EAGAIN;
> }
> if (ret == -ERESTARTSYS)
> @@ -3166,6 +3188,7 @@ static int io_recvmsg(struct io_kiocb *req, struct io_kiocb **nxt,
>
> if (kmsg && kmsg->iov != kmsg->fast_iov)
> kfree(kmsg->iov);
> + req->flags &= ~REQ_F_NEED_CLEANUP;
> io_cqring_add_event(req, ret);
> if (ret < 0)
> req_set_fail_links(req);
> @@ -4176,6 +4199,30 @@ static int io_req_defer(struct io_kiocb *req, const struct io_uring_sqe *sqe)
> return -EIOCBQUEUED;
> }
>
> +static void io_cleanup_req(struct io_kiocb *req)
> +{
> + struct io_async_ctx *io = req->io;
> +
> + switch (req->opcode) {
> + case IORING_OP_READV:
> + case IORING_OP_READ_FIXED:
> + case IORING_OP_READ:
> + case IORING_OP_WRITEV:
> + case IORING_OP_WRITE_FIXED:
> + case IORING_OP_WRITE:
> + if (io->rw.iov != io->rw.fast_iov)
> + kfree(io->rw.iov);
> + break;
> + case IORING_OP_SENDMSG:
> + case IORING_OP_RECVMSG:
> + if (io->msg.iov != io->msg.fast_iov)
> + kfree(io->msg.iov);
> + break;
> + }
> +
> + req->flags &= ~REQ_F_NEED_CLEANUP;
> +}
> +
> static int io_issue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
> struct io_kiocb **nxt, bool force_nonblock)
> {
>

--
Pavel Begunkov

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