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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>
This commit is contained in:
Nikolay Aleksandrov 2013-10-24 12:09:24 +02:00 committed by David S. Miller
parent 45e526e80e
commit c7c6effdef
1 changed files with 3 additions and 7 deletions
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10
drivers/net/netconsole.c
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@ -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;
}