netfilter: ensure number of counters is >0 in do_replace()

After improving setsockopt() coverage in trinity, I started triggering
vmalloc failures pretty reliably from this code path:

warn_alloc_failed+0xe9/0x140
__vmalloc_node_range+0x1be/0x270
vzalloc+0x4b/0x50
__do_replace+0x52/0x260 [ip_tables]
do_ipt_set_ctl+0x15d/0x1d0 [ip_tables]
nf_setsockopt+0x65/0x90
ip_setsockopt+0x61/0xa0
raw_setsockopt+0x16/0x60
sock_common_setsockopt+0x14/0x20
SyS_setsockopt+0x71/0xd0

It turns out we don't validate that the num_counters field in the
struct we pass in from userspace is initialized.

The same problem also exists in ebtables, arptables, ipv6, and the
compat variants.

Signed-off-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 1a732a1d3c8e..62f5b0d0bc9b 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -1275,6 +1275,9 @@ 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;
+        if (tmp.num_counters == 0)
+                return -EINVAL;
+
         tmp.name[sizeof(tmp.name)-1] = 0;
 
         newinfo = xt_alloc_table_info(tmp.size);
@@ -1822,6 +1825,9 @@ 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;
+        if (tmp.num_counters == 0)
+                return -EINVAL;
+
         tmp.name[sizeof(tmp.name)-1] = 0;
 
         newinfo = xt_alloc_table_info(tmp.size);