From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A3BAC43381 for ; Wed, 27 Mar 2019 18:58:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D0D2E2075C for ; Wed, 27 Mar 2019 18:58:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553713118; bh=MSo0u1jGOEaroxkvuEdEFti/DU0XOeTCR5vg8pBF0Kw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=qYmBRtmN9wVVbbxSWFV4oAxIxFkdA9l9WP8pAPswgJjZhUsOrF4CkEhbs0fGXzaO2 xEWjDRK6wbOwI8MbhMh/Hxcw6y0T0H99UufVvC8t3bo/cJxteTYiIN0b+dWfC5vPPN O3r5TQUZm4I5RUwokTrK7xtxwSANoew5AVM/MIpU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389867AbfC0S6b (ORCPT ); Wed, 27 Mar 2019 14:58:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:59248 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388767AbfC0SPi (ORCPT ); Wed, 27 Mar 2019 14:15:38 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E003A21741; Wed, 27 Mar 2019 18:15:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553710537; bh=MSo0u1jGOEaroxkvuEdEFti/DU0XOeTCR5vg8pBF0Kw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=K3agCSO8ZtzFlyTYk0utqwvaUdczJHKSvwYZMojEod2z2XtSY/dn/cFrh/gUuuazj xlTrSB67PF/AqbsAcie33m7kMfKwyO3Mee5AQLTShwskPubGtdn2QM4JZ0TB4zFx7K F4CoJYqn8uTiP3HFoiiFUXC51yOfdeKgpfyuuSYg= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Marcel Holtmann , Johan Hedberg , Sasha Levin , linux-bluetooth@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 163/192] Bluetooth: Verify that l2cap_get_conf_opt provides large enough buffer Date: Wed, 27 Mar 2019 14:09:55 -0400 Message-Id: <20190327181025.13507-163-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190327181025.13507-1-sashal@kernel.org> References: <20190327181025.13507-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-bluetooth-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org From: Marcel Holtmann [ Upstream commit 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 ] The function l2cap_get_conf_opt will return L2CAP_CONF_OPT_SIZE + opt->len as length value. The opt->len however is in control over the remote user and can be used by an attacker to gain access beyond the bounds of the actual packet. To prevent any potential leak of heap memory, it is enough to check that the resulting len calculation after calling l2cap_get_conf_opt is not below zero. A well formed packet will always return >= 0 here and will end with the length value being zero after the last option has been parsed. In case of malformed packets messing with the opt->len field the length value will become negative. If that is the case, then just abort and ignore the option. In case an attacker uses a too short opt->len value, then garbage will be parsed, but that is protected by the unknown option handling and also the option parameter size checks. Signed-off-by: Marcel Holtmann Reviewed-by: Greg Kroah-Hartman Signed-off-by: Johan Hedberg Signed-off-by: Sasha Levin --- net/bluetooth/l2cap_core.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index d17a4736e47c..6c873dc549b0 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -3336,6 +3336,8 @@ static int l2cap_parse_conf_req(struct l2cap_chan *chan, void *data, size_t data while (len >= L2CAP_CONF_OPT_SIZE) { len -= l2cap_get_conf_opt(&req, &type, &olen, &val); + if (len < 0) + break; hint = type & L2CAP_CONF_HINT; type &= L2CAP_CONF_MASK; @@ -3547,6 +3549,8 @@ static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len, while (len >= L2CAP_CONF_OPT_SIZE) { len -= l2cap_get_conf_opt(&rsp, &type, &olen, &val); + if (len < 0) + break; switch (type) { case L2CAP_CONF_MTU: @@ -3727,6 +3731,8 @@ static void l2cap_conf_rfc_get(struct l2cap_chan *chan, void *rsp, int len) while (len >= L2CAP_CONF_OPT_SIZE) { len -= l2cap_get_conf_opt(&rsp, &type, &olen, &val); + if (len < 0) + break; switch (type) { case L2CAP_CONF_RFC: -- 2.19.1