Patch "netfilter: x_tables: check standard target size too" has been added to the 4.6-stable tree

Patch "netfilter: x_tables: check standard target size too" 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: check standard target size too

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-check-standard-target-size-too.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 7ed2abddd20cf8f6bd27f65bd218f26fa5bf7f44 Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@strlen.de>
Date: Fri, 1 Apr 2016 14:17:27 +0200
Subject: netfilter: x_tables: check standard target size too

From: Florian Westphal <fw@strlen.de>

commit 7ed2abddd20cf8f6bd27f65bd218f26fa5bf7f44 upstream.

We have targets and standard targets -- the latter carries a verdict.

The ip/ip6tables validation functions will access t->verdict for the
standard targets to fetch the jump offset or verdict for chainloop
detection, but this happens before the targets get checked/validated.

Thus we also need to check for verdict presence here, else t->verdict
can point right after a blob.

Spotted with UBSAN while testing malformed blobs.

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/netfilter/x_tables.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -540,6 +540,13 @@ int xt_compat_match_to_user(const struct
 }
 EXPORT_SYMBOL_GPL(xt_compat_match_to_user);
 
+/* non-compat version may have padding after verdict */
+struct compat_xt_standard_target {
+	struct compat_xt_entry_target t;
+	compat_uint_t verdict;
+};
+
+/* see xt_check_entry_offsets */
 int xt_compat_check_entry_offsets(const void *base,
 				  unsigned int target_offset,
 				  unsigned int next_offset)
@@ -557,6 +564,10 @@ int xt_compat_check_entry_offsets(const
 	if (target_offset + t->u.target_size > next_offset)
 		return -EINVAL;
 
+	if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 &&
+	    target_offset + sizeof(struct compat_xt_standard_target) != next_offset)
+		return -EINVAL;
+
 	return 0;
 }
 EXPORT_SYMBOL(xt_compat_check_entry_offsets);
@@ -596,6 +607,10 @@ int xt_check_entry_offsets(const void *b
 	if (target_offset + t->u.target_size > next_offset)
 		return -EINVAL;
 
+	if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 &&
+	    target_offset + sizeof(struct xt_standard_target) != next_offset)
+		return -EINVAL;
+
 	return 0;
 }
 EXPORT_SYMBOL(xt_check_entry_offsets);


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