linux-kernel - [PATCH] [31/106] netfilter: arp_tables: fix infoleak to userspace

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Date:	Tue, 26 Apr 2011 14:13:10 -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] [31/106] netfilter: arp_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 42eab94fff18cb1091d3501cd284d6bd6cc9c143 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 bug was introduced before the git epoch;  the second is
introduced by 6b7d31fc (v2.6.15-rc1);  the third is introduced by
6b7d31fc (v2.6.15-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/arp_tables.c |    3 +++
 1 file changed, 3 insertions(+)

Index: linux-2.6.35.y/net/ipv4/netfilter/arp_tables.c
===================================================================
--- linux-2.6.35.y.orig/net/ipv4/netfilter/arp_tables.c
+++ linux-2.6.35.y/net/ipv4/netfilter/arp_tables.c
@@ -1081,6 +1081,7 @@ static int do_replace(struct net *net, c
 	/* 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)
@@ -1502,6 +1503,7 @@ static int compat_do_replace(struct net 
 		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)
@@ -1754,6 +1756,7 @@ static int do_arpt_get_ctl(struct sock *
 			ret = -EFAULT;
 			break;
 		}
+		rev.name[sizeof(rev.name)-1] = 0;
 
 		try_then_request_module(xt_find_revision(NFPROTO_ARP, rev.name,
 							 rev.revision, 1, &ret),
--
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