linux-kernel - [PATCH] [30/106] netfilter: ip_tables: fix infoleak to userspace

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Date:	Tue, 26 Apr 2011 14:13:09 -0700 (PDT)
From:	Andi Kleen <andi@...stfloor.org>
To:	segoon@...nwall.com, kaber@...sh.net, gregkh@...e.de,
	ak@...ux.intel.com, linux-kernel@...r.kernel.org,
	stable@...nel.org, tim.bird@...sony.com
Subject: [PATCH] [30/106] netfilter: ip_tables: fix infoleak to userspace

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Vasiliy Kulikov <segoon@...nwall.com>

commit 78b79876761b86653df89c48a7010b5cbd41a84a upstream.

Structures ipt_replace, compat_ipt_replace, and xt_get_revision are
copied from userspace.  Fields of these structs that are
zero-terminated strings are not checked.  When they are used as argument
to a format string containing "%s" in request_module(), some sensitive
information is leaked to userspace via argument of spawned modprobe
process.

The first and the third bugs were introduced before the git epoch; the
second was introduced in 2722971c (v2.6.17-rc1).  To trigger the bug
one should have CAP_NET_ADMIN.

Signed-off-by: Vasiliy Kulikov <segoon@...nwall.com>
Signed-off-by: Patrick McHardy <kaber@...sh.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
Signed-off-by: Andi Kleen <ak@...ux.intel.com>

---
 net/ipv4/netfilter/ip_tables.c |    3 +++
 1 file changed, 3 insertions(+)

Index: linux-2.6.35.y/net/ipv4/netfilter/ip_tables.c
===================================================================
--- linux-2.6.35.y.orig/net/ipv4/netfilter/ip_tables.c
+++ linux-2.6.35.y/net/ipv4/netfilter/ip_tables.c
@@ -1273,6 +1273,7 @@ do_replace(struct net *net, const void _
 	/* overflow check */
 	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
 		return -ENOMEM;
+	tmp.name[sizeof(tmp.name)-1] = 0;
 
 	newinfo = xt_alloc_table_info(tmp.size);
 	if (!newinfo)
@@ -1817,6 +1818,7 @@ compat_do_replace(struct net *net, void 
 		return -ENOMEM;
 	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
 		return -ENOMEM;
+	tmp.name[sizeof(tmp.name)-1] = 0;
 
 	newinfo = xt_alloc_table_info(tmp.size);
 	if (!newinfo)
@@ -2046,6 +2048,7 @@ do_ipt_get_ctl(struct sock *sk, int cmd,
 			ret = -EFAULT;
 			break;
 		}
+		rev.name[sizeof(rev.name)-1] = 0;
 
 		if (cmd == IPT_SO_GET_REVISION_TARGET)
 			target = 1;
--
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