diff options
| author | Xin Long <lucien.xin@gmail.com> | 2019-03-08 14:50:54 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-03-19 13:12:39 +0100 |
| commit | eaa0962e1eb255fca499b891b79fe9ec2f39e073 (patch) | |
| tree | 4da2924fd86faa00f7dfd9e382b1c8d78b3c96d0 /net/ipv4 | |
| parent | ec61b95340f892f5a62bda5d04e8283563175445 (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/ipv4')
| -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 a9824366f101..7a556e459375 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1308,6 +1308,10 @@ 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; |