From: Florian Westphal <fw@strlen.de>
Date: Sat, 6 Jan 2018 00:13:08 +0000 (+0100)
Subject: xfrm: don't call xfrm_policy_cache_flush while holding spinlock
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=b1bdcb59b64f806ef08d25a85c39ffb3ad841ce6;p=linux.git

xfrm: don't call xfrm_policy_cache_flush while holding spinlock

xfrm_policy_cache_flush can sleep, so it cannot be called while holding
a spinlock.  We could release the lock first, but I don't see why we need
to invoke this function here in first place, the packet path won't reuse
an xdst entry unless its still valid.

While at it, add an annotation to xfrm_policy_cache_flush, it would
have probably caught this bug sooner.

Fixes: ec30d78c14a813 ("xfrm: add xdst pcpu cache")
Reported-by: syzbot+e149f7d1328c26f9c12f@syzkaller.appspotmail.com
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 2ef6db98e9ba3..bc5eae12fb097 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -975,8 +975,6 @@ int xfrm_policy_flush(struct net *net, u8 type, bool task_valid)
 	}
 	if (!cnt)
 		err = -ESRCH;
-	else
-		xfrm_policy_cache_flush();
 out:
 	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 	return err;
@@ -1744,6 +1742,8 @@ void xfrm_policy_cache_flush(void)
 	bool found = 0;
 	int cpu;
 
+	might_sleep();
+
 	local_bh_disable();
 	rcu_read_lock();
 	for_each_possible_cpu(cpu) {