3.16.72-rc1 review patch. If anyone has any objections, please let me know.
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From: Malte Leip malte@leip.net
commit c409ca3be3c6ff3a1eeb303b191184e80d412862 upstream.
Change the validation of number_of_packets in get_pipe to compare the number of packets to a fixed maximum number of packets allowed, set to be 1024. This number was chosen due to it being used by other drivers as well, for example drivers/usb/host/uhci-q.c
Background/reason: The get_pipe function in stub_rx.c validates the number of packets in isochronous mode and aborts with an error if that number is too large, in order to prevent malicious input from possibly triggering large memory allocations. This was previously done by checking whether pdu->u.cmd_submit.number_of_packets is bigger than the number of packets that would be needed for pdu->u.cmd_submit.transfer_buffer_length bytes if all except possibly the last packet had maximum length, given by usb_endpoint_maxp(epd) * usb_endpoint_maxp_mult(epd). This leads to an error if URBs with packets shorter than the maximum possible length are submitted, which is allowed according to Documentation/driver-api/usb/URB.rst and occurs for example with the snd-usb-audio driver.
Fixes: c6688ef9f297 ("usbip: fix stub_rx: harden CMD_SUBMIT path to handle malicious input") Signed-off-by: Malte Leip malte@leip.net Acked-by: Shuah Khan skhan@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [bwh: Backported to 3.16: adjust filenames] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/staging/usbip/stub_rx.c | 12 +++--------- drivers/staging/usbip/usbip_common.h | 7 +++++++ 2 files changed, 10 insertions(+), 9 deletions(-)
--- a/drivers/staging/usbip/stub_rx.c +++ b/drivers/staging/usbip/stub_rx.c @@ -375,16 +375,10 @@ static int get_pipe(struct stub_device * }
if (usb_endpoint_xfer_isoc(epd)) { - /* validate packet size and number of packets */ - unsigned int maxp, packets, bytes; - - maxp = usb_endpoint_maxp(epd); - maxp *= usb_endpoint_maxp_mult(epd); - bytes = pdu->u.cmd_submit.transfer_buffer_length; - packets = DIV_ROUND_UP(bytes, maxp); - + /* validate number of packets */ if (pdu->u.cmd_submit.number_of_packets < 0 || - pdu->u.cmd_submit.number_of_packets > packets) { + pdu->u.cmd_submit.number_of_packets > + USBIP_MAX_ISO_PACKETS) { dev_err(&sdev->udev->dev, "CMD_SUBMIT: isoc invalid num packets %d\n", pdu->u.cmd_submit.number_of_packets); --- a/drivers/staging/usbip/usbip_common.h +++ b/drivers/staging/usbip/usbip_common.h @@ -134,6 +134,13 @@ extern struct device_attribute dev_attr_ #define USBIP_DIR_OUT 0x00 #define USBIP_DIR_IN 0x01
+/* + * Arbitrary limit for the maximum number of isochronous packets in an URB, + * compare for example the uhci_submit_isochronous function in + * drivers/usb/host/uhci-q.c + */ +#define USBIP_MAX_ISO_PACKETS 1024 + /** * struct usbip_header_basic - data pertinent to every request * @command: the usbip request type