Patch "netfilter: x_tables: don't move to non-existent next rule" has been added to the 4.6-stable tree

Patch "netfilter: x_tables: don't move to non-existent next rule" has been added to the 4.6-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    netfilter: x_tables: don't move to non-existent next rule

to the 4.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     netfilter-x_tables-don-t-move-to-non-existent-next-rule.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From f24e230d257af1ad7476c6e81a8dc3127a74204e Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@strlen.de>
Date: Fri, 1 Apr 2016 14:17:21 +0200
Subject: netfilter: x_tables: don't move to non-existent next rule

From: Florian Westphal <fw@strlen.de>

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.

Reported-by: Ben Hawkes <hawkes@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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(-)

--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -439,6 +439,8 @@ static int mark_source_chains(const stru
 				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 stru
 				} else {
 					/* ... this is a fallthru */
 					newpos = pos + e->next_offset;
+					if (newpos >= newinfo->size)
+						return 0;
 				}
 				e = (struct arpt_entry *)
 					(entry0 + newpos);
@@ -691,10 +695,8 @@ static int translate_table(struct xt_tab
 		}
 	}
 
-	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;
--- 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
 				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 {
@@ -541,6 +543,8 @@ mark_source_chains(const struct xt_table
 				} else {
 					/* ... this is a fallthru */
 					newpos = pos + e->next_offset;
+					if (newpos >= newinfo->size)
+						return 0;
 				}
 				e = (struct ipt_entry *)
 					(entry0 + newpos);
--- 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
 				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
 				} else {
 					/* ... this is a fallthru */
 					newpos = pos + e->next_offset;
+					if (newpos >= newinfo->size)
+						return 0;
 				}
 				e = (struct ip6t_entry *)
 					(entry0 + newpos);


Patches currently in stable-queue which might be from fw@strlen.de are

queue-4.6/netfilter-x_tables-add-and-use-xt_check_entry_offsets.patch
queue-4.6/netfilter-x_tables-assert-minimum-target-size.patch
queue-4.6/netfilter-x_tables-add-compat-version-of-xt_check_entry_offsets.patch
queue-4.6/netfilter-x_tables-check-for-bogus-target-offset.patch
queue-4.6/netfilter-x_tables-validate-targets-of-jumps.patch
queue-4.6/netfilter-x_tables-don-t-move-to-non-existent-next-rule.patch
queue-4.6/netfilter-x_tables-kill-check_entry-helper.patch
queue-4.6/netfilter-x_tables-check-standard-target-size-too.patch
queue-4.6/netfilter-x_tables-validate-all-offsets-and-sizes-in-a-rule.patch