From: Vasiliy Kulikov Date: Tue, 15 Mar 2011 12:35:21 +0000 (+0100) Subject: netfilter: arp_tables: fix infoleak to userspace X-Git-Url: http://git.alex.org.uk netfilter: arp_tables: fix infoleak to userspace BugLink: http://bugs.launchpad.net/bugs/761134 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 Signed-off-by: Patrick McHardy Signed-off-by: Greg Kroah-Hartman Signed-off-by: Tim Gardner --- diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index e855fff..6d79aa1 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -1065,6 +1065,7 @@ 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) @@ -1486,6 +1487,7 @@ 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) @@ -1738,6 +1740,7 @@ 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),