From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Westphal Subject: [PATCH 5/5] netfilter: x_tables: don't move to non-existant next rule Date: Tue, 22 Mar 2016 18:02:53 +0100 Message-ID: <1458666173-24318-6-git-send-email-fw@strlen.de> References: <1458666173-24318-1-git-send-email-fw@strlen.de> Cc: Florian Westphal To: Return-path: Received: from Chamillionaire.breakpoint.cc ([80.244.247.6]:38142 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752874AbcCVRCx (ORCPT ); Tue, 22 Mar 2016 13:02:53 -0400 In-Reply-To: <1458666173-24318-1-git-send-email-fw@strlen.de> Sender: netfilter-devel-owner@vger.kernel.org List-ID: Ben Hawkes reported an out-of-bounds write in mark_source_chains(). This was caused by improper underflow check -- we should have bailed earlier. The underflow check has been fixed in the preceeding change ("netfilter: x_tables: fix unconditional helper"). Just to be safe also add checks to mark_source_chains() in case we have other bugs that would cause such a condition. Signed-off-by: Florian Westphal --- 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 a2002ff..13266f4 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -439,6 +439,8 @@ 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 { @@ -461,6 +463,8 @@ 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); @@ -682,10 +686,8 @@ 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 45b1d97..c4836f0 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -520,6 +520,8 @@ mark_source_chains(const struct xt_table_info *newinfo, size = e->next_offset; e = (struct ipt_entry *) (entry0 + pos + size); + if (WARN_ON(pos + size >= newinfo->size)) + return 0; e->counters.pcnt = pos; pos += size; } else { @@ -541,6 +543,8 @@ mark_source_chains(const struct xt_table_info *newinfo, } else { /* ... this is a fallthru */ newpos = pos + e->next_offset; + if (WARN_ON(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 85c0942..ab7cdbf 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -532,6 +532,8 @@ 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 { @@ -553,6 +555,8 @@ 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); -- 2.4.10