From: Ziyang Xuan william.xuanziyang@huawei.com
[ Upstream commit 06a0716949c22e2aefb648526580671197151acc ]
Now in addrconf_mod_rs_timer(), reference idev depends on whether rs_timer is not pending. Then modify rs_timer timeout.
There is a time gap in [1], during which if the pending rs_timer becomes not pending. It will miss to hold idev, but the rs_timer is activated. Thus rs_timer callback function addrconf_rs_timer() will be executed and put idev later without holding idev. A refcount underflow issue for idev can be caused by this.
if (!timer_pending(&idev->rs_timer)) in6_dev_hold(idev); <--------------[1] mod_timer(&idev->rs_timer, jiffies + when);
To fix the issue, hold idev if mod_timer() return 0.
Fixes: b7b1bfce0bb6 ("ipv6: split duplicate address detection and router solicitation timer") Suggested-by: Eric Dumazet edumazet@google.com Signed-off-by: Ziyang Xuan william.xuanziyang@huawei.com Reviewed-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv6/addrconf.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 0d3e76b160a5b..6703a5b65e4a6 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -325,9 +325,8 @@ static void addrconf_del_dad_work(struct inet6_ifaddr *ifp) static void addrconf_mod_rs_timer(struct inet6_dev *idev, unsigned long when) { - if (!timer_pending(&idev->rs_timer)) + if (!mod_timer(&idev->rs_timer, jiffies + when)) in6_dev_hold(idev); - mod_timer(&idev->rs_timer, jiffies + when); }
static void addrconf_mod_dad_work(struct inet6_ifaddr *ifp,