Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.7 16/59] cdc-acm: added sanity checking for probe() | Date | Mon, 12 Sep 2016 17:29:36 +0200 |
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4.7-stable review patch. If anyone has any objections, please let me know.
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From: Oliver Neukum <oneukum@suse.com>
This is an alternative to eccf2a4e6b64d249929acc1f7aaa2ab0fb199d3d which inadvertedly fixes an oops in probe by a device returning malformed descriptors. The problem allows a malicious device to attack the kernel. That patch in v4.8 is too extensive to backport to stable. Thus this alternative fix is needed up to v4.7
Signed-off-by: Oliver Neukum <oneukum@suse.com> Reported-by: Binyamin Sharet <bsharet@cisco.com> Tested-by: Binyamin Sharet <bsharet@cisco.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/usb/class/cdc-acm.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)
--- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -1196,6 +1196,8 @@ static int acm_probe(struct usb_interfac } if (!buflen) { + if (!intf->cur_altsetting || !intf->cur_altsetting->endpoint) + return -EINVAL; if (intf->cur_altsetting->endpoint && intf->cur_altsetting->endpoint->extralen && intf->cur_altsetting->endpoint->extra) { @@ -1276,6 +1278,8 @@ next_desc: data_interface = usb_ifnum_to_if(usb_dev, (data_interface_num = call_interface_num)); control_interface = intf; } else { + if (!intf->cur_altsetting) + return -ENODEV; if (intf->cur_altsetting->desc.bNumEndpoints != 3) { dev_dbg(&intf->dev,"No union descriptor, giving up\n"); return -ENODEV; @@ -1305,15 +1309,22 @@ next_desc: combined_interfaces = 1; /* a popular other OS doesn't use it */ quirks |= NO_CAP_LINE; + if (!data_interface->cur_altsetting) + return -EINVAL; if (data_interface->cur_altsetting->desc.bNumEndpoints != 3) { dev_err(&intf->dev, "This needs exactly 3 endpoints\n"); return -EINVAL; } look_for_collapsed_interface: + if (!data_interface->cur_altsetting) + return -EINVAL; for (i = 0; i < 3; i++) { struct usb_endpoint_descriptor *ep; ep = &data_interface->cur_altsetting->endpoint[i].desc; + if (!ep) + return -ENODEV; + if (usb_endpoint_is_int_in(ep)) epctrl = ep; else if (usb_endpoint_is_bulk_out(ep)) @@ -1332,8 +1343,12 @@ look_for_collapsed_interface: skip_normal_probe: /*workaround for switched interfaces */ + if (!data_interface->cur_altsetting) + return -EINVAL; if (data_interface->cur_altsetting->desc.bInterfaceClass != CDC_DATA_INTERFACE_TYPE) { + if (!control_interface->cur_altsetting) + return -EINVAL; if (control_interface->cur_altsetting->desc.bInterfaceClass == CDC_DATA_INTERFACE_TYPE) { dev_dbg(&intf->dev, @@ -1356,6 +1371,7 @@ skip_normal_probe: if (data_interface->cur_altsetting->desc.bNumEndpoints < 2 || + !control_interface->cur_altsetting || control_interface->cur_altsetting->desc.bNumEndpoints == 0) return -EINVAL; @@ -1363,6 +1379,8 @@ skip_normal_probe: epread = &data_interface->cur_altsetting->endpoint[0].desc; epwrite = &data_interface->cur_altsetting->endpoint[1].desc; + if (!epctrl || !epread || !epwrite) + return -ENODEV; /* workaround for switched endpoints */ if (!usb_endpoint_dir_in(epread)) {
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