From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933177AbcHUPoD (ORCPT ); Sun, 21 Aug 2016 11:44:03 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:55885 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932987AbcHUPfl (ORCPT ); Sun, 21 Aug 2016 11:35:41 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Florian Westphal , Pablo Neira Ayuso , Willy Tarreau Subject: [PATCH 3.10 012/180] netfilter: x_tables: check standard target size too Date: Sun, 21 Aug 2016 17:29:02 +0200 Message-Id: <1471793510-13022-13-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1471793510-13022-1-git-send-email-w@1wt.eu> References: <1471793510-13022-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Florian Westphal 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 Signed-off-by: Pablo Neira Ayuso Signed-off-by: Willy Tarreau --- net/netfilter/x_tables.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index eeb4edc..37f7eda 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -559,6 +559,13 @@ int xt_compat_match_to_user(const struct xt_entry_match *m, } 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) @@ -576,6 +583,10 @@ int xt_compat_check_entry_offsets(const void *base, 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); @@ -615,6 +626,10 @@ int xt_check_entry_offsets(const void *base, 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); -- 2.8.0.rc2.1.gbe9624a