[Bluetooth] Fix L2CAP and HCI setsockopt() information leaks
The L2CAP and HCI setsockopt() implementations have a small information
leak that makes it possible to leak kernel stack memory to userspace.
If the optlen parameter is 0, no data will be copied by copy_from_user(),
but the uninitialized stack buffer will be read and stored later. A call
to getsockopt() can now retrieve the leaked information.
To fix this problem the stack buffer given to copy_from_user() must be
initialized with the current settings.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
index 832b5f4..bfc9a35 100644
--- a/net/bluetooth/hci_sock.c
+++ b/net/bluetooth/hci_sock.c
@@ -499,6 +499,15 @@
break;
case HCI_FILTER:
+ {
+ struct hci_filter *f = &hci_pi(sk)->filter;
+
+ uf.type_mask = f->type_mask;
+ uf.opcode = f->opcode;
+ uf.event_mask[0] = *((u32 *) f->event_mask + 0);
+ uf.event_mask[1] = *((u32 *) f->event_mask + 1);
+ }
+
len = min_t(unsigned int, len, sizeof(uf));
if (copy_from_user(&uf, optval, len)) {
err = -EFAULT;
diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index a586787..a59b1fb 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -954,11 +954,17 @@
switch (optname) {
case L2CAP_OPTIONS:
+ opts.imtu = l2cap_pi(sk)->imtu;
+ opts.omtu = l2cap_pi(sk)->omtu;
+ opts.flush_to = l2cap_pi(sk)->flush_to;
+ opts.mode = 0x00;
+
len = min_t(unsigned int, sizeof(opts), optlen);
if (copy_from_user((char *) &opts, optval, len)) {
err = -EFAULT;
break;
}
+
l2cap_pi(sk)->imtu = opts.imtu;
l2cap_pi(sk)->omtu = opts.omtu;
break;