io_uring/net: commit partial buffers on retry

Commit 41b70df5b38bc80967d2e0ed55cc3c3896bba781 upstream.

Ring provided buffers are potentially only valid within the single
execution context in which they were acquired. io_uring deals with this
and invalidates them on retry. But on the networking side, if
MSG_WAITALL is set, or if the socket is of the streaming type and too
little was processed, then it will hang on to the buffer rather than
recycle or commit it. This is problematic for two reasons:

1) If someone unregisters the provided buffer ring before a later retry,
   then the req->buf_list will no longer be valid.

2) If multiple sockers are using the same buffer group, then multiple
   receives can consume the same memory. This can cause data corruption
   in the application, as either receive could land in the same
   userspace buffer.

Fix this by disallowing partial retries from pinning a provided buffer
across multiple executions, if ring provided buffers are used.

Cc: stable@vger.kernel.org
Reported-by: pt x <superman.xpt@gmail.com>
Fixes: c56e022c0a27 ("io_uring: add support for user mapped provided buffer ring")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/io_uring/net.c b/io_uring/net.c
index e455f051e62ef7c53b437c8ed18873350264bc78..e7f8a79e049c9d75f1744f1f0c6302854c69f528 100644 (file)
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -351,6 +351,13 @@ static int io_setup_async_addr(struct io_kiocb *req,
        return -EAGAIN;
 }
 
+static void io_net_kbuf_recyle(struct io_kiocb *req)
+{
+       req->flags |= REQ_F_PARTIAL_IO;
+       if (req->flags & REQ_F_BUFFER_RING)
+               io_kbuf_recycle_ring(req);
+}
+
 int io_sendmsg_prep_async(struct io_kiocb *req)
 {
        int ret;
@@ -442,7 +449,7 @@ int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
                        kmsg->msg.msg_controllen = 0;
                        kmsg->msg.msg_control = NULL;
                        sr->done_io += ret;
-                       req->flags |= REQ_F_PARTIAL_IO;
+                       io_net_kbuf_recyle(req);
                        return io_setup_async_msg(req, kmsg, issue_flags);
                }
                if (ret == -ERESTARTSYS)
@@ -521,7 +528,7 @@ int io_send(struct io_kiocb *req, unsigned int issue_flags)
                        sr->len -= ret;
                        sr->buf += ret;
                        sr->done_io += ret;
-                       req->flags |= REQ_F_PARTIAL_IO;
+                       io_net_kbuf_recyle(req);
                        return io_setup_async_addr(req, &__address, issue_flags);
                }
                if (ret == -ERESTARTSYS)
@@ -891,7 +898,7 @@ retry_multishot:
                }
                if (ret > 0 && io_net_retry(sock, flags)) {
                        sr->done_io += ret;
-                       req->flags |= REQ_F_PARTIAL_IO;
+                       io_net_kbuf_recyle(req);
                        return io_setup_async_msg(req, kmsg, issue_flags);
                }
                if (ret == -ERESTARTSYS)
@@ -991,7 +998,7 @@ retry_multishot:
                        sr->len -= ret;
                        sr->buf += ret;
                        sr->done_io += ret;
-                       req->flags |= REQ_F_PARTIAL_IO;
+                       io_net_kbuf_recyle(req);
                        return -EAGAIN;
                }
                if (ret == -ERESTARTSYS)
@@ -1235,7 +1242,7 @@ int io_send_zc(struct io_kiocb *req, unsigned int issue_flags)
                        zc->len -= ret;
                        zc->buf += ret;
                        zc->done_io += ret;
-                       req->flags |= REQ_F_PARTIAL_IO;
+                       io_net_kbuf_recyle(req);
                        return io_setup_async_addr(req, &__address, issue_flags);
                }
                if (ret == -ERESTARTSYS)
@@ -1306,7 +1313,7 @@ int io_sendmsg_zc(struct io_kiocb *req, unsigned int issue_flags)
 
                if (ret > 0 && io_net_retry(sock, flags)) {
                        sr->done_io += ret;
-                       req->flags |= REQ_F_PARTIAL_IO;
+                       io_net_kbuf_recyle(req);
                        return io_setup_async_msg(req, kmsg, issue_flags);
                }
                if (ret == -ERESTARTSYS)