From: kaber@trash.net
To: davem@davemloft.net
Cc: netfilter-devel@vger.kernel.org, netdev@vger.kernel.org
Subject: [PATCH 3/4] netfilter: xtables: fix reentrancy
Date: Sun, 20 Mar 2011 16:32:27 +0100 [thread overview]
Message-ID: <1300635148-22648-4-git-send-email-kaber@trash.net> (raw)
In-Reply-To: <1300635148-22648-1-git-send-email-kaber@trash.net>
From: Eric Dumazet <eric.dumazet@gmail.com>
commit f3c5c1bfd4308 (make ip_tables reentrant) introduced a race in
handling the stackptr restore, at the end of ipt_do_table()
We should do it before the call to xt_info_rdunlock_bh(), or we allow
cpu preemption and another cpu overwrites stackptr of original one.
A second fix is to change the underflow test to check the origptr value
instead of 0 to detect underflow, or else we allow a jump from different
hooks.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
---
net/ipv4/netfilter/ip_tables.c | 4 ++--
net/ipv6/netfilter/ip6_tables.c | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index b09ed0d..ffcea0d 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -387,7 +387,7 @@ ipt_do_table(struct sk_buff *skb,
verdict = (unsigned)(-v) - 1;
break;
}
- if (*stackptr == 0) {
+ if (*stackptr <= origptr) {
e = get_entry(table_base,
private->underflow[hook]);
pr_debug("Underflow (this is normal) "
@@ -427,10 +427,10 @@ ipt_do_table(struct sk_buff *skb,
/* Verdict */
break;
} while (!acpar.hotdrop);
- xt_info_rdunlock_bh();
pr_debug("Exiting %s; resetting sp from %u to %u\n",
__func__, *stackptr, origptr);
*stackptr = origptr;
+ xt_info_rdunlock_bh();
#ifdef DEBUG_ALLOW_ALL
return NF_ACCEPT;
#else
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index c9598a9..0b2af9b 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -410,7 +410,7 @@ ip6t_do_table(struct sk_buff *skb,
verdict = (unsigned)(-v) - 1;
break;
}
- if (*stackptr == 0)
+ if (*stackptr <= origptr)
e = get_entry(table_base,
private->underflow[hook]);
else
@@ -441,8 +441,8 @@ ip6t_do_table(struct sk_buff *skb,
break;
} while (!acpar.hotdrop);
- xt_info_rdunlock_bh();
*stackptr = origptr;
+ xt_info_rdunlock_bh();
#ifdef DEBUG_ALLOW_ALL
return NF_ACCEPT;
--
1.7.4
next prev parent reply other threads:[~2011-03-20 15:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-20 15:32 [PATCH 0/4] netfilter: netfilter fixes kaber
2011-03-20 15:32 ` [PATCH 1/4] netfilter: ipset: fix address ranges at hash:*port* types kaber
2011-03-20 15:32 ` [PATCH 2/4] netfilter: ipset: fix checking the type revision at create command kaber
2011-03-20 15:32 ` kaber [this message]
2011-03-20 15:32 ` [PATCH 4/4] netfilter: ipt_CLUSTERIP: fix buffer overflow kaber
2011-03-20 20:42 ` [PATCH 0/4] netfilter: netfilter fixes David Miller
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