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From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org
Subject: [PATCH net 1/4] netfilter: xt_recent: Fix attempt to update deleted entry
Date: Fri,  5 Feb 2021 01:17:24 +0100	[thread overview]
Message-ID: <20210205001727.2125-2-pablo@netfilter.org> (raw)
In-Reply-To: <20210205001727.2125-1-pablo@netfilter.org>

From: Jozsef Kadlecsik <kadlec@mail.kfki.hu>

When both --reap and --update flag are specified, there's a code
path at which the entry to be updated is reaped beforehand,
which then leads to kernel crash. Reap only entries which won't be
updated.

Fixes kernel bugzilla #207773.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=207773
Reported-by: Reindl Harald <h.reindl@thelounge.net>
Fixes: 0079c5aee348 ("netfilter: xt_recent: add an entry reaper")
Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/xt_recent.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/xt_recent.c b/net/netfilter/xt_recent.c
index 606411869698..0446307516cd 100644
--- a/net/netfilter/xt_recent.c
+++ b/net/netfilter/xt_recent.c
@@ -152,7 +152,8 @@ static void recent_entry_remove(struct recent_table *t, struct recent_entry *e)
 /*
  * Drop entries with timestamps older then 'time'.
  */
-static void recent_entry_reap(struct recent_table *t, unsigned long time)
+static void recent_entry_reap(struct recent_table *t, unsigned long time,
+			      struct recent_entry *working, bool update)
 {
 	struct recent_entry *e;
 
@@ -161,6 +162,12 @@ static void recent_entry_reap(struct recent_table *t, unsigned long time)
 	 */
 	e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
 
+	/*
+	 * Do not reap the entry which are going to be updated.
+	 */
+	if (e == working && update)
+		return;
+
 	/*
 	 * The last time stamp is the most recent.
 	 */
@@ -303,7 +310,8 @@ recent_mt(const struct sk_buff *skb, struct xt_action_param *par)
 
 		/* info->seconds must be non-zero */
 		if (info->check_set & XT_RECENT_REAP)
-			recent_entry_reap(t, time);
+			recent_entry_reap(t, time, e,
+				info->check_set & XT_RECENT_UPDATE && ret);
 	}
 
 	if (info->check_set & XT_RECENT_SET ||
-- 
2.20.1


  reply	other threads:[~2021-02-05  0:18 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-05  0:17 [PATCH net 0/4] Netfilter fixes for net Pablo Neira Ayuso
2021-02-05  0:17 ` Pablo Neira Ayuso [this message]
2021-02-05  5:50   ` [PATCH net 1/4] netfilter: xt_recent: Fix attempt to update deleted entry patchwork-bot+netdevbpf
2021-02-05 11:33   ` Reindl Harald
2021-02-05 13:54     ` Jozsef Kadlecsik
2021-02-05 14:42       ` Reindl Harald
2021-02-07 16:34         ` Reindl Harald
2021-02-07 19:38           ` Jozsef Kadlecsik
2021-02-10 10:34             ` Reindl Harald
2021-02-13 16:09               ` Reindl Harald
2021-02-13 16:21                 ` Reindl Harald
2021-02-15  7:21               ` Jozsef Kadlecsik
2021-02-07 19:36         ` Jozsef Kadlecsik
2021-02-05  0:17 ` [PATCH net 2/4] selftests: netfilter: fix current year Pablo Neira Ayuso
2021-02-05  0:17 ` [PATCH net 3/4] netfilter: nftables: fix possible UAF over chains from packet path in netns Pablo Neira Ayuso
2021-02-05  0:17 ` [PATCH net 4/4] netfilter: flowtable: fix tcp and udp header checksum update Pablo Neira Ayuso

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