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Subject[34-longterm 244/247] ipv6: netfilter: ip6_tables: fix infoleak to userspace
From: Vasiliy Kulikov <>

This is a commit scheduled for the next v2.6.34 longterm release.
If you see a problem with using this for longterm, please comment.

commit 6a8ab060779779de8aea92ce3337ca348f973f54 upstream.

Structures ip6t_replace, compat_ip6t_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

The first bug was introduced before the git epoch; the second was
introduced in 3bc3fe5e (v2.6.25-rc1); the third is introduced by
6b7d31fc (v2.6.15-rc1). To trigger the bug one should have

Signed-off-by: Vasiliy Kulikov <>
Signed-off-by: Patrick McHardy <>
Signed-off-by: Paul Gortmaker <>
net/ipv6/netfilter/ip6_tables.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 9210e31..542edbf 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -1325,6 +1325,7 @@ do_replace(struct net *net, const void __user *user, unsigned int len)
/* overflow check */
if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
return -ENOMEM;
+[sizeof(] = 0;

newinfo = xt_alloc_table_info(tmp.size);
if (!newinfo)
@@ -1871,6 +1872,7 @@ compat_do_replace(struct net *net, void __user *user, unsigned int len)
return -ENOMEM;
if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
return -ENOMEM;
+[sizeof(] = 0;

newinfo = xt_alloc_table_info(tmp.size);
if (!newinfo)
@@ -2100,6 +2102,7 @@ do_ip6t_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
ret = -EFAULT;
+[sizeof(] = 0;

target = 1;

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