[PATCH] io_uring: fix deferred req iovec leak

Pavel Begunkov
2020-02-06T16:52:05Z

After defer, a request will be prepared, that includes allocating iovec
if needed, and then submitted through io_wq_submit_work() but not custom
handler (e.g. io_rw_async()/io_sendrecv_async()). However, it'll leak
iovec, as it's in io-wq and the code goes as follows:

io_read() {
if (!io_wq_current_is_worker())
kfree(iovec);
}

Put all deallocation logic in io_{read,write,send,recv}(), which will
leave the memory, if going async with -EAGAIN.

It also fixes a leak after failed io_alloc_async_ctx() in
io_{recv,send}_msg().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 47 ++++++++++++-----------------------------------
1 file changed, 12 insertions(+), 35 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index bff7a03e873f..ce3dbd2b1b5c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2143,17 +2143,6 @@ static int io_alloc_async_ctx(struct io_kiocb *req)
return req->io == NULL;
}

-static void io_rw_async(struct io_wq_work **workptr)
-{
- struct io_kiocb *req = container_of(*workptr, struct io_kiocb, work);
- struct iovec *iov = NULL;
-
- if (req->io->rw.iov != req->io->rw.fast_iov)
- iov = req->io->rw.iov;
- io_wq_submit_work(workptr);
- kfree(iov);
-}
-
static int io_setup_async_rw(struct io_kiocb *req, ssize_t io_size,
struct iovec *iovec, struct iovec *fast_iov,
struct iov_iter *iter)
@@ -2166,7 +2155,6 @@ static int io_setup_async_rw(struct io_kiocb *req, ssize_t io_size,

io_req_map_rw(req, io_size, iovec, fast_iov, iter);
}
- req->work.func = io_rw_async;
return 0;
}

@@ -2253,8 +2241,7 @@ static int io_read(struct io_kiocb *req, struct io_kiocb **nxt,
}
}
out_free:
- if (!io_wq_current_is_worker())
- kfree(iovec);
+ kfree(iovec);
return ret;
}

@@ -2359,8 +2346,7 @@ static int io_write(struct io_kiocb *req, struct io_kiocb **nxt,
}
}
out_free:
- if (!io_wq_current_is_worker())
- kfree(iovec);
+ kfree(iovec);
return ret;
}

@@ -2955,19 +2941,6 @@ static int io_sync_file_range(struct io_kiocb *req, struct io_kiocb **nxt,
return 0;
}

-#if defined(CONFIG_NET)
-static void io_sendrecv_async(struct io_wq_work **workptr)
-{
- struct io_kiocb *req = container_of(*workptr, struct io_kiocb, work);
- struct iovec *iov = NULL;
-
- if (req->io->rw.iov != req->io->rw.fast_iov)
- iov = req->io->msg.iov;
- io_wq_submit_work(workptr);
- kfree(iov);
-}
-#endif
-
static int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
#if defined(CONFIG_NET)
@@ -3036,17 +3009,19 @@ static int io_sendmsg(struct io_kiocb *req, struct io_kiocb **nxt,
if (force_nonblock && ret == -EAGAIN) {
if (req->io)
return -EAGAIN;
- if (io_alloc_async_ctx(req))
+ if (io_alloc_async_ctx(req)) {
+ if (kmsg && kmsg->iov != kmsg->fast_iov)
+ kfree(kmsg->iov);
return -ENOMEM;
+ }
memcpy(&req->io->msg, &io.msg, sizeof(io.msg));
- req->work.func = io_sendrecv_async;
return -EAGAIN;
}
if (ret == -ERESTARTSYS)
ret = -EINTR;
}

- if (!io_wq_current_is_worker() && kmsg && kmsg->iov != kmsg->fast_iov)
+ if (kmsg && kmsg->iov != kmsg->fast_iov)
kfree(kmsg->iov);
io_cqring_add_event(req, ret);
if (ret < 0)
@@ -3180,17 +3155,19 @@ static int io_recvmsg(struct io_kiocb *req, struct io_kiocb **nxt,
if (force_nonblock && ret == -EAGAIN) {
if (req->io)
return -EAGAIN;
- if (io_alloc_async_ctx(req))
+ if (io_alloc_async_ctx(req)) {
+ if (kmsg && kmsg->iov != kmsg->fast_iov)
+ kfree(kmsg->iov);
return -ENOMEM;
+ }
memcpy(&req->io->msg, &io.msg, sizeof(io.msg));
- req->work.func = io_sendrecv_async;
return -EAGAIN;
}
if (ret == -ERESTARTSYS)
ret = -EINTR;
}

- if (!io_wq_current_is_worker() && kmsg && kmsg->iov != kmsg->fast_iov)
+ if (kmsg && kmsg->iov != kmsg->fast_iov)
kfree(kmsg->iov);
io_cqring_add_event(req, ret);
if (ret < 0)
--
2.24.0