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    Subject[PATCH AUTOSEL 4.9 11/35] USB: hso: Fix OOB memory access in hso_probe/hso_get_config_data
    Date
    From: Hui Peng <benquike@gmail.com>

    [ Upstream commit 5146f95df782b0ac61abde36567e718692725c89 ]

    The function hso_probe reads if_num from the USB device (as an u8) and uses
    it without a length check to index an array, resulting in an OOB memory read
    in hso_probe or hso_get_config_data.

    Add a length check for both locations and updated hso_probe to bail on
    error.

    This issue has been assigned CVE-2018-19985.

    Reported-by: Hui Peng <benquike@gmail.com>
    Reported-by: Mathias Payer <mathias.payer@nebelwelt.net>
    Signed-off-by: Hui Peng <benquike@gmail.com>
    Signed-off-by: Mathias Payer <mathias.payer@nebelwelt.net>
    Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/net/usb/hso.c | 18 ++++++++++++++++--
    1 file changed, 16 insertions(+), 2 deletions(-)

    diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
    index e7b516342678..66ae647b712e 100644
    --- a/drivers/net/usb/hso.c
    +++ b/drivers/net/usb/hso.c
    @@ -2808,6 +2808,12 @@ static int hso_get_config_data(struct usb_interface *interface)
    return -EIO;
    }

    + /* check if we have a valid interface */
    + if (if_num > 16) {
    + kfree(config_data);
    + return -EINVAL;
    + }
    +
    switch (config_data[if_num]) {
    case 0x0:
    result = 0;
    @@ -2878,10 +2884,18 @@ static int hso_probe(struct usb_interface *interface,

    /* Get the interface/port specification from either driver_info or from
    * the device itself */
    - if (id->driver_info)
    + if (id->driver_info) {
    + /* if_num is controlled by the device, driver_info is a 0 terminated
    + * array. Make sure, the access is in bounds! */
    + for (i = 0; i <= if_num; ++i)
    + if (((u32 *)(id->driver_info))[i] == 0)
    + goto exit;
    port_spec = ((u32 *)(id->driver_info))[if_num];
    - else
    + } else {
    port_spec = hso_get_config_data(interface);
    + if (port_spec < 0)
    + goto exit;
    + }

    /* Check if we need to switch to alt interfaces prior to port
    * configuration */
    --
    2.19.1
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