Commit c7c6effd authored by Nikolay Aleksandrov's avatar Nikolay Aleksandrov Committed by David S. Miller
Browse files

netconsole: fix multiple race conditions 



In every netconsole option that can be set through configfs there's a
race when checking for nt->enabled since it can be modified at the same
time. Probably the most damage can be done by store_enabled when racing
with another instance of itself. Fix all the races with one stone by
moving the mutex lock around the ->store call for all options.

Signed-off-by: default avatarNikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 45e526e8

drivers/net/netconsole.c

+3 −7
Original line number Diff line number Diff line
@@ -325,9 +325,7 @@ static ssize_t store_enabled(struct netconsole_target *nt, 
		return -EINVAL;

	}



	mutex_lock(&nt->mutex);

	if (enabled) {	/* 1 */



		/*

		 * Skip netpoll_parse_options() -- all the attributes are

		 * already configured via configfs. Just print them out.
@@ -335,13 +333,10 @@ static ssize_t store_enabled(struct netconsole_target *nt, 
		netpoll_print_options(&nt->np);



		err = netpoll_setup(&nt->np);

		if (err) {

			mutex_unlock(&nt->mutex);

		if (err)

			return err;

		}



		printk(KERN_INFO "netconsole: network logging started\n");



	} else {	/* 0 */

		/* We need to disable the netconsole before cleaning it up

		 * otherwise we might end up in write_msg() with
@@ -354,7 +349,6 @@ static ssize_t store_enabled(struct netconsole_target *nt, 
	}



	nt->enabled = enabled;

	mutex_unlock(&nt->mutex);



	return strnlen(buf, count);

}
@@ -571,8 +565,10 @@ static ssize_t netconsole_target_attr_store(struct config_item *item, 
	struct netconsole_target_attr *na =

		container_of(attr, struct netconsole_target_attr, attr);



	mutex_lock(&nt->mutex);

	if (na->store)

		ret = na->store(nt, buf, count);

	mutex_unlock(&nt->mutex);



	return ret;

}

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