[PATCH] Bluetooth: Fix incorrect strncpy() in hidp_setup_hid()

[PATCH] Bluetooth: Fix incorrect strncpy() in hidp_setup_hid()

[Anderson Lizardo]

The length parameter should be sizeof(req->name) - 1 because there is no
guarantee that string provided by userspace will contain the trailing
'\0'.

Can be easily reproduced by manually setting req->name to 128 non-zero
bytes prior to ioctl(HIDPCONNADD) and checking the device name setup on
input subsystem:

$ cat /sys/devices/pnp0/00\:04/tty/ttyS0/hci0/hci0\:1/input8/name
AAAAAA[...]AAAAAAAAf0:af:f0:af:f0:af

("f0:af:f0:af:f0:af" is the device bluetooth address, taken from "phys"
field in struct hid_device due to overflow.)

Signed-off-by: Anderson Lizardo <anderson.lizardo@openbossa.org>
---
 net/bluetooth/hidp/core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bluetooth/hidp/core.c b/net/bluetooth/hidp/core.c
index 0c00284..33600b4 100644
--- a/net/bluetooth/hidp/core.c
+++ b/net/bluetooth/hidp/core.c
@@ -931,7 +931,7 @@ static int hidp_setup_hid(struct hidp_session *session,
 	hid->version = req->version;
 	hid->country = req->country;
 
-	strncpy(hid->name, req->name, 128);
+	strncpy(hid->name, req->name, sizeof(req->name) - 1);
 
 	snprintf(hid->phys, sizeof(hid->phys), "%pMR",
 		 &bt_sk(session->ctrl_sock->sk)->src);
-- 
1.7.9.5

Re: [PATCH] Bluetooth: Fix incorrect strncpy() in hidp_setup_hid()

[Marcel Holtmann]

Hi Anderson,

> The length parameter should be sizeof(req->name) - 1 because there is no
> guarantee that string provided by userspace will contain the trailing
> '\0'.
> 
> Can be easily reproduced by manually setting req->name to 128 non-zero
> bytes prior to ioctl(HIDPCONNADD) and checking the device name setup on
> input subsystem:
> 
> $ cat /sys/devices/pnp0/00\:04/tty/ttyS0/hci0/hci0\:1/input8/name
> AAAAAA[...]AAAAAAAAf0:af:f0:af:f0:af
> 
> ("f0:af:f0:af:f0:af" is the device bluetooth address, taken from "phys"
> field in struct hid_device due to overflow.)
> 
> Signed-off-by: Anderson Lizardo <anderson.lizardo@openbossa.org>
> ---
>  net/bluetooth/hidp/core.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

this is a good catch. And this should also go to -stable and the current
kernels right away.

It is actually a security issue since it leaks kernel memory to
userspace.

Acked-by: Marcel Holtmann <marcel@holtmann.org>

Regards

Marcel

Re: [PATCH] Bluetooth: Fix incorrect strncpy() in hidp_setup_hid()

[Gustavo Padovan]

Hi Anderson,

* Anderson Lizardo <anderson.lizardo@openbossa.org> [2013-01-06 18:28:53 -0400]:

> The length parameter should be sizeof(req->name) - 1 because there is no
> guarantee that string provided by userspace will contain the trailing
> '\0'.
> 
> Can be easily reproduced by manually setting req->name to 128 non-zero
> bytes prior to ioctl(HIDPCONNADD) and checking the device name setup on
> input subsystem:
> 
> $ cat /sys/devices/pnp0/00\:04/tty/ttyS0/hci0/hci0\:1/input8/name
> AAAAAA[...]AAAAAAAAf0:af:f0:af:f0:af
> 
> ("f0:af:f0:af:f0:af" is the device bluetooth address, taken from "phys"
> field in struct hid_device due to overflow.)
> 
> Signed-off-by: Anderson Lizardo <anderson.lizardo@openbossa.org>
> ---
>  net/bluetooth/hidp/core.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Patch has been applied to bluetooth.git. Thanks. I'm also sending it to
stable.

	Gustavo