From: Ignat Korchagin <ignat.korchagin@xxxxxxxxx>
commit b348d7dddb6c4fbfc810b7a0626e8ec9e29f7cbb upstream.
Fix potential out-of-bounds write to urb->transfer_buffer
usbip handles network communication directly in the kernel. When receiving a
packet from its peer, usbip code parses headers according to protocol. As
part of this parsing urb->actual_length is filled. Since the input for
urb->actual_length comes from the network, it should be treated as untrusted.
Any entity controlling the network may put any value in the input and the
preallocated urb->transfer_buffer may not be large enough to hold the data.
Thus, the malicious entity is able to write arbitrary data to kernel memory.
Signed-off-by: Ignat Korchagin <ignat.korchagin@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
[Patch appears in 4.6-rc3 and has been picked up by a couple of the older
3.x releases, but not (yet?) in any of the maintained 4.x kernels.
Was not originally tagged with Cc stable ; Fixes CVE-2016-3955 issue.]
drivers/usb/usbip/usbip_common.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/usb/usbip/usbip_common.c b/drivers/usb/usbip/usbip_common.c
index facaaf003f19..e40da7759a0e 100644
--- a/drivers/usb/usbip/usbip_common.c
+++ b/drivers/usb/usbip/usbip_common.c
@@ -741,6 +741,17 @@ int usbip_recv_xbuff(struct usbip_device *ud, struct urb *urb)
if (!(size > 0))
return 0;
+ if (size > urb->transfer_buffer_length) {
+ /* should not happen, probably malicious packet */
+ if (ud->side == USBIP_STUB) {
+ usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
+ return 0;
+ } else {
+ usbip_event_add(ud, VDEV_EVENT_ERROR_TCP);
+ return -EPIPE;
+ }
+ }
+
ret = usbip_recv(ud->tcp_socket, urb->transfer_buffer, size);
if (ret != size) {
dev_err(&urb->dev->dev, "recv xbuf, %d\n", ret);
--
2.5.0
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