mainline inclusion from mainline-v6.5-rc2 commit 06a0716949c22e2aefb648526580671197151acc category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I7M991 CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... --------------------------- 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: Ziyang Xuan <william.xuanziyang@huawei.com> --- 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 9d8b791f63ef..b4f4e751e3a7 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -316,9 +316,8 @@ 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, -- 2.25.1