batman-adv: Fix integer overflow in batadv_iv_ogm_calc_tq
authorSven Eckelmann <sven.eckelmann@open-mesh.com>
Tue, 16 Feb 2016 09:47:07 +0000 (10:47 +0100)
committerAntonio Quartulli <a@unstable.cc>
Wed, 18 May 2016 03:49:42 +0000 (11:49 +0800)
commitd285f52cc0f23564fd61976d43fd5b991b4828f6
treecb94178c532da21ddc3a53a82665bcaef9e1645a
parent1653f61d656516aae7130db19561258a847d1e94
batman-adv: Fix integer overflow in batadv_iv_ogm_calc_tq

The undefined behavior sanatizer detected an signed integer overflow in a
setup with near perfect link quality

    UBSAN: Undefined behaviour in net/batman-adv/bat_iv_ogm.c:1246:25
    signed integer overflow:
    8713350 * 255 cannot be represented in type 'int'

The problems happens because the calculation of mixed unsigned and signed
integers resulted in an integer multiplication.

      batadv_ogm_packet::tq (u8 255)
    * tq_own (u8 255)
    * tq_asym_penalty (int 134; max 255)
    * tq_iface_penalty (int 255; max 255)

The tq_iface_penalty, tq_asym_penalty and inv_asym_penalty can just be
changed to unsigned int because they are not expected to become negative.

Fixes: c039876892e3 ("batman-adv: add WiFi penalty")
Signed-off-by: Sven Eckelmann <sven.eckelmann@open-mesh.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
net/batman-adv/bat_iv_ogm.c