netdev - [PATCH 04/10] xfrm: policy: delete inexact policies from inexact list on hash rebuild

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 25 Jan 2019 08:44:20 +0100
From:   Steffen Klassert <steffen.klassert@...unet.com>
To:     David Miller <davem@...emloft.net>
CC:     Herbert Xu <herbert@...dor.apana.org.au>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        <netdev@...r.kernel.org>
Subject: [PATCH 04/10] xfrm: policy: delete inexact policies from inexact list on hash rebuild

From: Florian Westphal <fw@...len.de>

An xfrm hash rebuild has to reset the inexact policy list before the
policies get re-inserted: A change of hash thresholds will result in
policies to get moved from inexact tree to the policy hash table.

If the thresholds are increased again later, they get moved from hash
table to inexact tree.

We must unlink all policies from the inexact tree before re-insertion.

Otherwise 'migrate' may find policies that are in main hash table a
second time, when it searches the inexact lists.

Furthermore, re-insertion without deletion can cause elements ->next to
point back to itself, causing soft lockups or double-frees.

Reported-by: syzbot+9d971dd21eb26567036b@...kaller.appspotmail.com
Fixes: 9cf545ebd591da ("xfrm: policy: store inexact policies in a tree ordered by destination address")
Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
---
 net/xfrm/xfrm_policy.c | 23 ++++++++++-------------
 1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index d8fba27a4bfb..24dfd1e47cf0 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -680,16 +680,6 @@ static void xfrm_hash_resize(struct work_struct *work)
 	mutex_unlock(&hash_resize_mutex);
 }
 
-static void xfrm_hash_reset_inexact_table(struct net *net)
-{
-	struct xfrm_pol_inexact_bin *b;
-
-	lockdep_assert_held(&net->xfrm.xfrm_policy_lock);
-
-	list_for_each_entry(b, &net->xfrm.inexact_bins, inexact_bins)
-		INIT_HLIST_HEAD(&b->hhead);
-}
-
 /* Make sure *pol can be inserted into fastbin.
  * Useful to check that later insert requests will be sucessful
  * (provided xfrm_policy_lock is held throughout).
@@ -1279,10 +1269,14 @@ static void xfrm_hash_rebuild(struct work_struct *work)
 	}
 
 	/* reset the bydst and inexact table in all directions */
-	xfrm_hash_reset_inexact_table(net);
-
 	for (dir = 0; dir < XFRM_POLICY_MAX; dir++) {
-		INIT_HLIST_HEAD(&net->xfrm.policy_inexact[dir]);
+		struct hlist_node *n;
+
+		hlist_for_each_entry_safe(policy, n,
+					  &net->xfrm.policy_inexact[dir],
+					  bydst_inexact_list)
+			hlist_del_init(&policy->bydst_inexact_list);
+
 		hmask = net->xfrm.policy_bydst[dir].hmask;
 		odst = net->xfrm.policy_bydst[dir].table;
 		for (i = hmask; i >= 0; i--)
@@ -1314,6 +1308,9 @@ static void xfrm_hash_rebuild(struct work_struct *work)
 		newpos = NULL;
 		chain = policy_hash_bysel(net, &policy->selector,
 					  policy->family, dir);
+
+		hlist_del_rcu(&policy->bydst);
+
 		if (!chain) {
 			void *p = xfrm_policy_inexact_insert(policy, dir, 0);
 
-- 
2.17.1