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Subject[patch 24/24] Bluetooth: Add packet size checks for CAPI messages (CVE-2006-6106)
2.6.18-stable review patch.  If anyone has any objections, please let us know.
------------------
From: Marcel Holtmann <holtmann@redhat.com>

With malformed packets it might be possible to overwrite internal
CMTP and CAPI data structures. This patch adds additional length
checks to prevent these kinds of remote attacks.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
net/bluetooth/cmtp/capi.c | 39 +++++++++++++++++++++++++++++++++------
1 file changed, 33 insertions(+), 6 deletions(-)
--- linux-2.6.18.5.orig/net/bluetooth/cmtp/capi.c
+++ linux-2.6.18.5/net/bluetooth/cmtp/capi.c
@@ -196,6 +196,9 @@ static void cmtp_recv_interopmsg(struct

switch (CAPIMSG_SUBCOMMAND(skb->data)) {
case CAPI_CONF:
+ if (skb->len < CAPI_MSG_BASELEN + 10)
+ break;
+
func = CAPIMSG_U16(skb->data, CAPI_MSG_BASELEN + 5);
info = CAPIMSG_U16(skb->data, CAPI_MSG_BASELEN + 8);

@@ -226,6 +229,9 @@ static void cmtp_recv_interopmsg(struct
break;

case CAPI_FUNCTION_GET_PROFILE:
+ if (skb->len < CAPI_MSG_BASELEN + 11 + sizeof(capi_profile))
+ break;
+
controller = CAPIMSG_U16(skb->data, CAPI_MSG_BASELEN + 11);
msgnum = CAPIMSG_MSGID(skb->data);

@@ -246,17 +252,26 @@ static void cmtp_recv_interopmsg(struct
break;

case CAPI_FUNCTION_GET_MANUFACTURER:
+ if (skb->len < CAPI_MSG_BASELEN + 15)
+ break;
+
controller = CAPIMSG_U32(skb->data, CAPI_MSG_BASELEN + 10);

if (!info && ctrl) {
+ int len = min_t(uint, CAPI_MANUFACTURER_LEN,
+ skb->data[CAPI_MSG_BASELEN + 14]);
+
+ memset(ctrl->manu, 0, CAPI_MANUFACTURER_LEN);
strncpy(ctrl->manu,
- skb->data + CAPI_MSG_BASELEN + 15,
- skb->data[CAPI_MSG_BASELEN + 14]);
+ skb->data + CAPI_MSG_BASELEN + 15, len);
}

break;

case CAPI_FUNCTION_GET_VERSION:
+ if (skb->len < CAPI_MSG_BASELEN + 32)
+ break;
+
controller = CAPIMSG_U32(skb->data, CAPI_MSG_BASELEN + 12);

if (!info && ctrl) {
@@ -269,13 +284,18 @@ static void cmtp_recv_interopmsg(struct
break;

case CAPI_FUNCTION_GET_SERIAL_NUMBER:
+ if (skb->len < CAPI_MSG_BASELEN + 17)
+ break;
+
controller = CAPIMSG_U32(skb->data, CAPI_MSG_BASELEN + 12);

if (!info && ctrl) {
+ int len = min_t(uint, CAPI_SERIAL_LEN,
+ skb->data[CAPI_MSG_BASELEN + 16]);
+
memset(ctrl->serial, 0, CAPI_SERIAL_LEN);
strncpy(ctrl->serial,
- skb->data + CAPI_MSG_BASELEN + 17,
- skb->data[CAPI_MSG_BASELEN + 16]);
+ skb->data + CAPI_MSG_BASELEN + 17, len);
}

break;
@@ -284,14 +304,18 @@ static void cmtp_recv_interopmsg(struct
break;

case CAPI_IND:
+ if (skb->len < CAPI_MSG_BASELEN + 6)
+ break;
+
func = CAPIMSG_U16(skb->data, CAPI_MSG_BASELEN + 3);

if (func == CAPI_FUNCTION_LOOPBACK) {
+ int len = min_t(uint, skb->len - CAPI_MSG_BASELEN - 6,
+ skb->data[CAPI_MSG_BASELEN + 5]);
appl = CAPIMSG_APPID(skb->data);
msgnum = CAPIMSG_MSGID(skb->data);
cmtp_send_interopmsg(session, CAPI_RESP, appl, msgnum, func,
- skb->data + CAPI_MSG_BASELEN + 6,
- skb->data[CAPI_MSG_BASELEN + 5]);
+ skb->data + CAPI_MSG_BASELEN + 6, len);
}

break;
@@ -309,6 +333,9 @@ void cmtp_recv_capimsg(struct cmtp_sessi

BT_DBG("session %p skb %p len %d", session, skb, skb->len);

+ if (skb->len < CAPI_MSG_BASELEN)
+ return;
+
if (CAPIMSG_COMMAND(skb->data) == CAPI_INTEROPERABILITY) {
cmtp_recv_interopmsg(session, skb);
return;
--
-
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