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netfilter: arp_tables: fix infoleak to userspace

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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@openwall.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Vasiliy Kulikov 2011-03-15 13:35:21 +01:00 committed by Patrick McHardy
parent 4656c4d61a
commit 42eab94fff
1 changed files with 3 additions and 0 deletions
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3
net/ipv4/netfilter/arp_tables.c
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@ -1066,6 +1066,7 @@ static int do_replace(struct net *net, const void __user *user,
/* 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)
@ -1488,6 +1489,7 @@ static int compat_do_replace(struct net *net, void __user *user,
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)
@ -1740,6 +1742,7 @@ static int do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len
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),