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: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 1505dcb..c9a1592 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -325,9 +325,7 @@
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 @@
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 @@
}
nt->enabled = enabled;
- mutex_unlock(&nt->mutex);
return strnlen(buf, count);
}
@@ -571,8 +565,10 @@
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;
}