From b1bdde33b72366da20d10770ab7a49fe87b5e190 Mon Sep 17 00:00:00 2001 From: Jozsef Kadlecsik Date: Fri, 29 Jan 2021 20:57:43 +0100 Subject: [PATCH] netfilter: xt_recent: Fix attempt to update deleted entry 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 Fixes: 0079c5aee348 ("netfilter: xt_recent: add an entry reaper") Signed-off-by: Jozsef Kadlecsik Signed-off-by: Pablo Neira Ayuso --- 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 6064118..0446307 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; @@ -162,6 +163,12 @@ 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. */ if (time_after(time, e->stamps[e->index-1])) @@ -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 || -- 2.7.4