From 82e2616ad251a3f72991036d6e8acebbd0aceb80 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Fri, 15 Jul 2016 15:08:15 -0400 Subject: [PATCH] netfilter: x_tables: don't move to non-existent next rule commit f24e230d257af1ad7476c6e81a8dc3127a74204e upstream. Ben Hawkes says: In the mark_source_chains function (net/ipv4/netfilter/ip_tables.c) it is possible for a user-supplied ipt_entry structure to have a large next_offset field. This field is not bounds checked prior to writing a counter value at the supplied offset. Base chains enforce absolute verdict. User defined chains are supposed to end with an unconditional return, xtables userspace adds them automatically. But if such return is missing we will move to non-existent next rule. CVE-2016-3134 Reported-by: Ben Hawkes Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Chas Williams <3chas3@gmail.com> Signed-off-by: Willy Tarreau --- net/ipv4/netfilter/arp_tables.c | 8 +++++--- net/ipv4/netfilter/ip_tables.c | 4 ++++ net/ipv6/netfilter/ip6_tables.c | 4 ++++ 3 files changed, 13 insertions(+), 3 deletions(-) diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index 456fc6efe05d..7460b7bef3ab 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -430,6 +430,8 @@ static int mark_source_chains(const struct xt_table_info *newinfo, size = e->next_offset; e = (struct arpt_entry *) (entry0 + pos + size); + if (pos + size >= newinfo->size) + return 0; e->counters.pcnt = pos; pos += size; } else { @@ -452,6 +454,8 @@ static int mark_source_chains(const struct xt_table_info *newinfo, } else { /* ... this is a fallthru */ newpos = pos + e->next_offset; + if (newpos >= newinfo->size) + return 0; } e = (struct arpt_entry *) (entry0 + newpos); @@ -675,10 +679,8 @@ static int translate_table(struct xt_table_info *newinfo, void *entry0, } } - if (!mark_source_chains(newinfo, repl->valid_hooks, entry0)) { - duprintf("Looping hook\n"); + if (!mark_source_chains(newinfo, repl->valid_hooks, entry0)) return -ELOOP; - } /* Finally, each sanity check must pass */ i = 0; diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index a5bd3c8eee84..8fc22eed9603 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -511,6 +511,8 @@ mark_source_chains(const struct xt_table_info *newinfo, size = e->next_offset; e = (struct ipt_entry *) (entry0 + pos + size); + if (pos + size >= newinfo->size) + return 0; e->counters.pcnt = pos; pos += size; } else { @@ -532,6 +534,8 @@ mark_source_chains(const struct xt_table_info *newinfo, } else { /* ... this is a fallthru */ newpos = pos + e->next_offset; + if (newpos >= newinfo->size) + return 0; } e = (struct ipt_entry *) (entry0 + newpos); diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c index fb8a146abed8..63f7876c4f29 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -521,6 +521,8 @@ mark_source_chains(const struct xt_table_info *newinfo, size = e->next_offset; e = (struct ip6t_entry *) (entry0 + pos + size); + if (pos + size >= newinfo->size) + return 0; e->counters.pcnt = pos; pos += size; } else { @@ -542,6 +544,8 @@ mark_source_chains(const struct xt_table_info *newinfo, } else { /* ... this is a fallthru */ newpos = pos + e->next_offset; + if (newpos >= newinfo->size) + return 0; } e = (struct ip6t_entry *) (entry0 + newpos); -- 2.20.1