2011-12-09 01:23:21

by Mat Martineau

Subject: [PATCHv2] Bluetooth: Prevent uninitialized data access in L2CAP configuration

When configuring an ERTM or streaming mode connection, remote devices
are expected to send an RFC option in a successful config response. A
misbehaving remote device might not send an RFC option, and the L2CAP
code should not access uninitialized data in this case.

Signed-off-by: Mat Martineau <[email protected]>
---
net/bluetooth/l2cap_core.c | 11 ++++++++++-
1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 5ea94a1..45dd423 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -2152,7 +2152,7 @@ static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len, voi
void *ptr = req->data;
int type, olen;
unsigned long val;
- struct l2cap_conf_rfc rfc;
+ struct l2cap_conf_rfc rfc = { .mode = L2CAP_MODE_BASIC };

BT_DBG("chan %p, rsp %p, len %d, req %p", chan, rsp, len, data);

@@ -2271,6 +2271,15 @@ static void l2cap_conf_rfc_get(struct l2cap_chan *chan, void *rsp, int len)
}
}

+ /* Use sane default values in case a misbehaving remote device
+ * did not send an RFC option.
+ */
+ BT_ERR("Expected RFC option was not found, using defaults");
+ rfc.mode = chan->mode;
+ rfc.retrans_timeout = cpu_to_le16(L2CAP_DEFAULT_RETRANS_TO);
+ rfc.monitor_timeout = cpu_to_le16(L2CAP_DEFAULT_MONITOR_TO);
+ rfc.max_pdu_size = cpu_to_le16(chan->imtu);
+
done:
switch (rfc.mode) {
case L2CAP_MODE_ERTM:
--
1.7.8

--
Mat Martineau
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum

2011-12-19 00:22:35

by Gustavo Padovan

Subject: Re: [PATCHv2] Bluetooth: Prevent uninitialized data access in L2CAP configuration

Hi Mat,

* Marcel Holtmann <[email protected]> [2011-12-09 10:06:15 +0200]:

> Hi Mat,
>
> > When configuring an ERTM or streaming mode connection, remote devices
> > are expected to send an RFC option in a successful config response. A
> > misbehaving remote device might not send an RFC option, and the L2CAP
> > code should not access uninitialized data in this case.
> >
> > Signed-off-by: Mat Martineau <[email protected]>
> > ---
> > net/bluetooth/l2cap_core.c | 11 ++++++++++-
> > 1 files changed, 10 insertions(+), 1 deletions(-)
> >
> > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> > index 5ea94a1..45dd423 100644
> > --- a/net/bluetooth/l2cap_core.c
> > +++ b/net/bluetooth/l2cap_core.c
> > @@ -2152,7 +2152,7 @@ static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len, voi
> > void *ptr = req->data;
> > int type, olen;
> > unsigned long val;
> > - struct l2cap_conf_rfc rfc;
> > + struct l2cap_conf_rfc rfc = { .mode = L2CAP_MODE_BASIC };
> >
> > BT_DBG("chan %p, rsp %p, len %d, req %p", chan, rsp, len, data);
> >
> > @@ -2271,6 +2271,15 @@ static void l2cap_conf_rfc_get(struct l2cap_chan *chan, void *rsp, int len)
> > }
> > }
> >
> > + /* Use sane default values in case a misbehaving remote device
> > + * did not send an RFC option.
> > + */
> > + BT_ERR("Expected RFC option was not found, using defaults");
> > + rfc.mode = chan->mode;
> > + rfc.retrans_timeout = cpu_to_le16(L2CAP_DEFAULT_RETRANS_TO);
> > + rfc.monitor_timeout = cpu_to_le16(L2CAP_DEFAULT_MONITOR_TO);
> > + rfc.max_pdu_size = cpu_to_le16(chan->imtu);
>
> I would actually put the BT_ERR afterwards the assignments separated
> with an extra empty line, but that is just to make it a bit easier on
> the eyes.

I applied this one with this change.

Gustavo

2011-12-09 08:06:15

by Marcel Holtmann

Subject: Re: [PATCHv2] Bluetooth: Prevent uninitialized data access in L2CAP configuration

Hi Mat,

> When configuring an ERTM or streaming mode connection, remote devices
> are expected to send an RFC option in a successful config response. A
> misbehaving remote device might not send an RFC option, and the L2CAP
> code should not access uninitialized data in this case.
>
> Signed-off-by: Mat Martineau <[email protected]>
> ---
> net/bluetooth/l2cap_core.c | 11 ++++++++++-
> 1 files changed, 10 insertions(+), 1 deletions(-)
>
> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> index 5ea94a1..45dd423 100644
> --- a/net/bluetooth/l2cap_core.c
> +++ b/net/bluetooth/l2cap_core.c
> @@ -2152,7 +2152,7 @@ static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len, voi
> void *ptr = req->data;
> int type, olen;
> unsigned long val;
> - struct l2cap_conf_rfc rfc;
> + struct l2cap_conf_rfc rfc = { .mode = L2CAP_MODE_BASIC };
>
> BT_DBG("chan %p, rsp %p, len %d, req %p", chan, rsp, len, data);
>
> @@ -2271,6 +2271,15 @@ static void l2cap_conf_rfc_get(struct l2cap_chan *chan, void *rsp, int len)
> }
> }
>
> + /* Use sane default values in case a misbehaving remote device
> + * did not send an RFC option.
> + */
> + BT_ERR("Expected RFC option was not found, using defaults");
> + rfc.mode = chan->mode;
> + rfc.retrans_timeout = cpu_to_le16(L2CAP_DEFAULT_RETRANS_TO);
> + rfc.monitor_timeout = cpu_to_le16(L2CAP_DEFAULT_MONITOR_TO);
> + rfc.max_pdu_size = cpu_to_le16(chan->imtu);

I would actually put the BT_ERR afterwards the assignments separated
with an extra empty line, but that is just to make it a bit easier on
the eyes.

> +
> done:
> switch (rfc.mode) {
> case L2CAP_MODE_ERTM:

Acked-by: Marcel Holtmann <[email protected]>

Regards

Marcel