diff options
| author | Xin Long <lucien.xin@gmail.com> | 2019-03-08 14:50:54 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-03-23 08:44:30 +0100 |
| commit | d31b540d63b19f60ae34195aab5644862ea0a683 (patch) | |
| tree | 7ce801bf35c4a38300c70ba133502391d2f93747 /net | |
| parent | d15bfd4603dc019dde6cd1f0298fbb10f176c44b (diff) | |
route: set the deleted fnhe fnhe_daddr to 0 in ip_del_fnhe to fix a race
[ Upstream commit ee60ad219f5c7c4fb2f047f88037770063ef785f ]
The race occurs in __mkroute_output() when 2 threads lookup a dst:
CPU A CPU B
find_exception()
find_exception() [fnhe expires]
ip_del_fnhe() [fnhe is deleted]
rt_bind_exception()
In rt_bind_exception() it will bind a deleted fnhe with the new dst, and
this dst will get no chance to be freed. It causes a dev defcnt leak and
consecutive dmesg warnings:
unregister_netdevice: waiting for ethX to become free. Usage count = 1
Especially thanks Jon to identify the issue.
This patch fixes it by setting fnhe_daddr to 0 in ip_del_fnhe() to stop
binding the deleted fnhe with a new dst when checking fnhe's fnhe_daddr
and daddr in rt_bind_exception().
It works as both ip_del_fnhe() and rt_bind_exception() are protected by
fnhe_lock and the fhne is freed by kfree_rcu().
Fixes: deed49df7390 ("route: check and remove route cache when we get route")
Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/route.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 80ce6b0672d2..97bf6c785767 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1604,6 +1604,10 @@ static void ip_del_fnhe(struct fib_nh *nh, __be32 daddr) if (fnhe->fnhe_daddr == daddr) { rcu_assign_pointer(*fnhe_p, rcu_dereference_protected( fnhe->fnhe_next, lockdep_is_held(&fnhe_lock))); + /* set fnhe_daddr to 0 to ensure it won't bind with + * new dsts in rt_bind_exception(). + */ + fnhe->fnhe_daddr = 0; fnhe_flush_routes(fnhe); kfree_rcu(fnhe, rcu); break; |