Commit ae4d37b5 authored Apr 06, 2022 by Xiaomeng Tong Committed by Jens Axboe Apr 06, 2022

drbd: fix an invalid memory access caused by incorrect use of list iterator



The bug is here:
	idr_remove(&connection->peer_devices, vnr);

If the previous for_each_connection() don't exit early (no goto hit
inside the loop), the iterator 'connection' after the loop will be a
bogus pointer to an invalid structure object containing the HEAD
(&resource->connections). As a result, the use of 'connection' above
will lead to a invalid memory access (including a possible invalid free
as idr_remove could call free_layer).

The original intention should have been to remove all peer_devices,
but the following lines have already done the work. So just remove
this line and the unneeded label, to fix this bug.

Cc: stable@vger.kernel.org
Fixes: c06ece6b ("drbd: Turn connection->volumes into connection->peer_devices")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
Reviewed-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent aadb22ba

drivers/block/drbd/drbd_main.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -2773,12 +2773,12 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig

		if (init_submitter(device)) {
		err = ERR_NOMEM;
		goto out_idr_remove_vol;
		goto out_idr_remove_from_resource;
		}

		err = add_disk(disk);
		if (err)
		goto out_idr_remove_vol;
		goto out_idr_remove_from_resource;

		/* inherit the connection state */
		device->state.conn = first_connection(resource)->cstate;
		@@ -2792,8 +2792,6 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig
		drbd_debugfs_device_add(device);
		return NO_ERROR;

		out_idr_remove_vol:
		idr_remove(&connection->peer_devices, vnr);
		out_idr_remove_from_resource:
		for_each_connection(connection, resource) {
		peer_device = idr_remove(&connection->peer_devices, vnr);