linux-kernel - [PATCH 3.16 118/136] Bluetooth: Prevent stack info leak from the EFS element.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <lsq.1518323471.227276522@decadent.org.uk>
Date:   Sun, 11 Feb 2018 04:31:11 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Ben Seri" <ben@...is.com>,
        "Johan Hedberg" <johan.hedberg@...il.com>,
        "Marcel Holtmann" <marcel@...tmann.org>,
        "Gustavo Padovan" <gustavo@...ovan.org>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>
Subject: [PATCH 3.16 118/136] Bluetooth: Prevent stack info leak from the
 EFS element.

3.16.54-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ben Seri <ben@...is.com>

commit 06e7e776ca4d36547e503279aeff996cbb292c16 upstream.

In the function l2cap_parse_conf_rsp and in the function
l2cap_parse_conf_req the following variable is declared without
initialization:

struct l2cap_conf_efs efs;

In addition, when parsing input configuration parameters in both of
these functions, the switch case for handling EFS elements may skip the
memcpy call that will write to the efs variable:

...
case L2CAP_CONF_EFS:
if (olen == sizeof(efs))
memcpy(&efs, (void *)val, olen);
...

The olen in the above if is attacker controlled, and regardless of that
if, in both of these functions the efs variable would eventually be
added to the outgoing configuration request that is being built:

l2cap_add_conf_opt(&ptr, L2CAP_CONF_EFS, sizeof(efs), (unsigned long) &efs);

So by sending a configuration request, or response, that contains an
L2CAP_CONF_EFS element, but with an element length that is not
sizeof(efs) - the memcpy to the uninitialized efs variable can be
avoided, and the uninitialized variable would be returned to the
attacker (16 bytes).

This issue has been assigned CVE-2017-1000410

Cc: Marcel Holtmann <marcel@...tmann.org>
Cc: Gustavo Padovan <gustavo@...ovan.org>
Cc: Johan Hedberg <johan.hedberg@...il.com>
Signed-off-by: Ben Seri <ben@...is.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/bluetooth/l2cap_core.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -3349,9 +3349,10 @@ static int l2cap_parse_conf_req(struct l
 			break;
 
 		case L2CAP_CONF_EFS:
-			remote_efs = 1;
-			if (olen == sizeof(efs))
+			if (olen == sizeof(efs)) {
+				remote_efs = 1;
 				memcpy(&efs, (void *) val, olen);
+			}
 			break;
 
 		case L2CAP_CONF_EWS:
@@ -3570,16 +3571,17 @@ static int l2cap_parse_conf_rsp(struct l
 			break;
 
 		case L2CAP_CONF_EFS:
-			if (olen == sizeof(efs))
+			if (olen == sizeof(efs)) {
 				memcpy(&efs, (void *)val, olen);
 
-			if (chan->local_stype != L2CAP_SERV_NOTRAFIC &&
-			    efs.stype != L2CAP_SERV_NOTRAFIC &&
-			    efs.stype != chan->local_stype)
-				return -ECONNREFUSED;
+				if (chan->local_stype != L2CAP_SERV_NOTRAFIC &&
+				    efs.stype != L2CAP_SERV_NOTRAFIC &&
+				    efs.stype != chan->local_stype)
+					return -ECONNREFUSED;
 
-			l2cap_add_conf_opt(&ptr, L2CAP_CONF_EFS, sizeof(efs),
-					   (unsigned long) &efs, endptr - ptr);
+				l2cap_add_conf_opt(&ptr, L2CAP_CONF_EFS, sizeof(efs),
+						   (unsigned long) &efs, endptr - ptr);
+			}
 			break;
 
 		case L2CAP_CONF_FCS: