[PATCH net] netconsole: fix multiple race conditions
From: Nikolay Aleksandrov <hidden>
Date: 2013-10-24 10:12:47
Subsystem:
netconsole, networking drivers, the rest · Maintainers:
Breno Leitao, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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 <redacted> --- Note: this patch is on top of netconsole: fix NULL pointer dereference that I posted yesterday. drivers/net/netconsole.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-)
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 @@ 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; }
--
1.8.1.4