From: Florian Westphal <fw@strlen.de>
Date: Tue, 13 Dec 2016 12:59:33 +0000 (+0100)
Subject: netfilter: nf_tables: fix oob access
X-Git-Tag: v3.18.85~5
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e72ebbefe1b222336bd11de0671f0d7ce76e1c6e;p=thirdparty%2Fkernel%2Fstable.git

netfilter: nf_tables: fix oob access


[ Upstream commit 3e38df136e453aa69eb4472108ebce2fb00b1ba6 ]

BUG: KASAN: slab-out-of-bounds in nf_tables_rule_destroy+0xf1/0x130 at addr ffff88006a4c35c8
Read of size 8 by task nft/1607

When we've destroyed last valid expr, nft_expr_next() returns an invalid expr.
We must not dereference it unless it passes != nft_expr_last() check.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 9fe2baa01fbea..74724560bc485 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1869,7 +1869,7 @@ static void nf_tables_rule_destroy(const struct nft_ctx *ctx,
 	 * is called on error from nf_tables_newrule().
 	 */
 	expr = nft_expr_first(rule);
-	while (expr->ops && expr != nft_expr_last(rule)) {
+	while (expr != nft_expr_last(rule) && expr->ops) {
 		nf_tables_expr_destroy(ctx, expr);
 		expr = nft_expr_next(expr);
 	}