net: set initial device refcount to 1
When adding CONFIG_PCPU_DEV_REFCNT, I forgot that the
initial net device refcount was 0.
When CONFIG_PCPU_DEV_REFCNT is not set, this means
the first dev_hold() triggers an illegal refcount
operation (addition on 0)
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 0 PID: 1 at lib/refcount.c:25 refcount_warn_saturate+0x128/0x1a4
Fix is to change initial (and final) refcount to be 1.
Also add a missing kerneldoc piece, as reported by
Stephen Rothwell.
Fixes: 919067cc845f ("net: add CONFIG_PCPU_DEV_REFCNT")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Guenter Roeck <groeck@google.com>
Tested-by: Guenter Roeck <groeck@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index ffab392..c9a496f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -10346,7 +10346,7 @@ static void netdev_wait_allrefs(struct net_device *dev)
rebroadcast_time = warning_time = jiffies;
refcnt = netdev_refcnt_read(dev);
- while (refcnt != 0) {
+ while (refcnt != 1) {
if (time_after(jiffies, rebroadcast_time + 1 * HZ)) {
rtnl_lock();
@@ -10383,7 +10383,7 @@ static void netdev_wait_allrefs(struct net_device *dev)
refcnt = netdev_refcnt_read(dev);
- if (refcnt && time_after(jiffies, warning_time + 10 * HZ)) {
+ if (refcnt != 1 && time_after(jiffies, warning_time + 10 * HZ)) {
pr_emerg("unregister_netdevice: waiting for %s to become free. Usage count = %d\n",
dev->name, refcnt);
warning_time = jiffies;
@@ -10459,7 +10459,7 @@ void netdev_run_todo(void)
netdev_wait_allrefs(dev);
/* paranoia */
- BUG_ON(netdev_refcnt_read(dev));
+ BUG_ON(netdev_refcnt_read(dev) != 1);
BUG_ON(!list_empty(&dev->ptype_all));
BUG_ON(!list_empty(&dev->ptype_specific));
WARN_ON(rcu_access_pointer(dev->ip_ptr));
@@ -10680,6 +10680,9 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
dev->pcpu_refcnt = alloc_percpu(int);
if (!dev->pcpu_refcnt)
goto free_dev;
+ dev_hold(dev);
+#else
+ refcount_set(&dev->dev_refcnt, 1);
#endif
if (dev_addr_init(dev))