From: YueHaibing <yuehaibing@huawei.com>
To: <steffen.klassert@secunet.com>, <herbert@gondor.apana.org.au>,
<davem@davemloft.net>, <kuba@kernel.org>, <timo.teras@iki.fi>
Cc: <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
YueHaibing <yuehaibing@huawei.com>
Subject: [PATCH v2] xfrm: policy: Fix doulbe free in xfrm_policy_timer
Date: Mon, 23 Mar 2020 09:41:55 +0800 [thread overview]
Message-ID: <20200323014155.56376-1-yuehaibing@huawei.com> (raw)
In-Reply-To: <20200318034839.57996-1-yuehaibing@huawei.com>
After xfrm_add_policy add a policy, its ref is 2, then
xfrm_policy_timer
read_lock
xp->walk.dead is 0
....
mod_timer()
xfrm_policy_kill
policy->walk.dead = 1
....
del_timer(&policy->timer)
xfrm_pol_put //ref is 1
xfrm_pol_put //ref is 0
xfrm_policy_destroy
call_rcu
xfrm_pol_hold //ref is 1
read_unlock
xfrm_pol_put //ref is 0
xfrm_policy_destroy
call_rcu
xfrm_policy_destroy is called twice, which may leads to
double free.
Call Trace:
RIP: 0010:refcount_warn_saturate+0x161/0x210
...
xfrm_policy_timer+0x522/0x600
call_timer_fn+0x1b3/0x5e0
? __xfrm_decode_session+0x2990/0x2990
? msleep+0xb0/0xb0
? _raw_spin_unlock_irq+0x24/0x40
? __xfrm_decode_session+0x2990/0x2990
? __xfrm_decode_session+0x2990/0x2990
run_timer_softirq+0x5c5/0x10e0
Fix this by use write_lock_bh in xfrm_policy_kill.
Fixes: ea2dea9dacc2 ("xfrm: remove policy lock when accessing policy->walk.dead")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
---
v2: Fix typo 'write_lock_bh'--> 'write_unlock_bh' while unlocking
---
net/xfrm/xfrm_policy.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index dbda08ec566e..ae0689174bbf 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -434,6 +434,7 @@ EXPORT_SYMBOL(xfrm_policy_destroy);
static void xfrm_policy_kill(struct xfrm_policy *policy)
{
+ write_lock_bh(&policy->lock);
policy->walk.dead = 1;
atomic_inc(&policy->genid);
@@ -445,6 +446,7 @@ static void xfrm_policy_kill(struct xfrm_policy *policy)
if (del_timer(&policy->timer))
xfrm_pol_put(policy);
+ write_unlock_bh(&policy->lock);
xfrm_pol_put(policy);
}
--
2.17.1
next prev parent reply other threads:[~2020-03-23 1:45 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-18 3:48 [PATCH] xfrm: policy: Fix doulbe free in xfrm_policy_timer YueHaibing
2020-03-23 1:41 ` YueHaibing [this message]
2020-03-23 6:29 ` [PATCH v2] " Herbert Xu
2020-03-23 7:04 ` Yuehaibing
2020-03-23 6:53 ` Timo Teras
2020-03-23 7:21 ` Yuehaibing
2020-03-23 7:56 ` Timo Teras
2020-03-23 7:32 ` [PATCH v3] " YueHaibing
2020-03-23 8:00 ` Timo Teras
2020-03-23 21:44 ` Herbert Xu
2020-03-25 12:53 ` Steffen Klassert
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