diff options
| author | Eric Dumazet <edumazet@google.com> | 2021-03-22 11:21:45 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-03-22 16:57:36 -0700 |
| commit | add2d73631070c951b0de81a01d1463a15cfbd47 (patch) | |
| tree | 17f432ad418341482f02ec52ef9daacc01e0ee77 | |
| parent | 0ca99c84df6b589b4673460c48ac4064181098cc (diff) | |
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>
| -rw-r--r-- | include/linux/netdevice.h | 1 | ||||
| -rw-r--r-- | net/core/dev.c | 9 |
2 files changed, 7 insertions, 3 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index e4a503288d9b..7005ad80e8d1 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1792,6 +1792,7 @@ enum netdev_ml_priv_type { * * @proto_down_reason: reason a netdev interface is held down * @pcpu_refcnt: Number of references to this device + * @dev_refcnt: Number of references to this device * @todo_list: Delayed register/unregister * @link_watch_list: XXX: need comments on this one * diff --git a/net/core/dev.c b/net/core/dev.c index ffab3928eeeb..c9a496f5e687 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)) |