From: Pavel Emelyanov Date: Thu, 31 Jul 2008 07:38:31 +0000 (-0700) Subject: netfilter: ipt_recent: fix race between recent_mt_destroy and proc manipulations X-Git-Tag: v2.6.27-rc2~102^2~8 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a8ddc9163c6a16cd62531dba1ec5020484e33b02;p=linux-2.6 netfilter: ipt_recent: fix race between recent_mt_destroy and proc manipulations The thing is that recent_mt_destroy first flushes the entries from table with the recent_table_flush and only *after* this removes the proc file, corresponding to that table. Thus, if we manage to write to this file the '+XXX' command we will leak some entries. If we manage to write there a 'clean' command we'll race in two recent_table_flush flows, since the recent_mt_destroy calls this outside the recent_lock. The proper solution as I see it is to remove the proc file first and then go on with flushing the table. This flushing becomes safe w/o the lock, since the table is already inaccessible from the outside. Signed-off-by: Pavel Emelyanov Signed-off-by: Patrick McHardy Signed-off-by: David S. Miller --- diff --git a/net/ipv4/netfilter/ipt_recent.c b/net/ipv4/netfilter/ipt_recent.c index 21cb053f5d..3974d7cae5 100644 --- a/net/ipv4/netfilter/ipt_recent.c +++ b/net/ipv4/netfilter/ipt_recent.c @@ -305,10 +305,10 @@ static void recent_mt_destroy(const struct xt_match *match, void *matchinfo) spin_lock_bh(&recent_lock); list_del(&t->list); spin_unlock_bh(&recent_lock); - recent_table_flush(t); #ifdef CONFIG_PROC_FS remove_proc_entry(t->name, proc_dir); #endif + recent_table_flush(t); kfree(t); } mutex_unlock(&recent_mutex);