This is a note to let you know that I've just added the patch titled
ipv6/addrconf: fix a potential refcount underflow for idev
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ipv6-addrconf-fix-a-potential-refcount-underflow-for.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit efe85c6893ae4fac909f925a76c4dd2c75b4015a
Author: Ziyang Xuan <william.xuanziyang@xxxxxxxxxx>
Date: Sat Jul 8 14:59:10 2023 +0800
ipv6/addrconf: fix a potential refcount underflow for idev
[ 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@xxxxxxxxxx>
Signed-off-by: Ziyang Xuan <william.xuanziyang@xxxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 6ba34f51c411f..e0d3909172a84 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -323,9 +323,8 @@ 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,
