From: Nikolay Aleksandrov Date: Thu, 24 Oct 2013 10:09:24 +0000 (+0200) Subject: netconsole: fix multiple race conditions X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=c7c6effdeffcafd792b9f880ad52e48689eea4ad;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git 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 Signed-off-by: David S. Miller --- diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c index 1505dcb950fa..c9a15925a1f7 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; }