Re: iptables: ensure number of counters is >0 in do_replace()
From: Florian Westphal <fw@strlen.de>
Date: 2015-05-19 23:19:50
Also in:
netfilter-devel
Dave Jones [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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. Signed-off-by: Dave Jones <redacted>diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index c69db7fa25ee..12a33d178614 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c@@ -1262,6 +1262,9 @@ 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; +
Good catch. Due to iptables wonderful copy-paste programming model, this also needs fixing in compat_do_replace, ip6tables, arbtables and ebtables (8 different places, ick).