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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: c039876892 ("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>
This commit is contained in:
Sven Eckelmann 2016-02-16 10:47:07 +01:00 committed by Antonio Quartulli
parent 1653f61d65
commit d285f52cc0
1 changed files with 3 additions and 2 deletions
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5
net/batman-adv/bat_iv_ogm.c
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@ -1180,9 +1180,10 @@ static bool batadv_iv_ogm_calc_tq(struct batadv_orig_node *orig_node,
u8 total_count;
u8 orig_eq_count, neigh_rq_count, neigh_rq_inv, tq_own;
unsigned int neigh_rq_inv_cube, neigh_rq_max_cube;
int tq_asym_penalty, inv_asym_penalty, if_num;
int if_num;
unsigned int tq_asym_penalty, inv_asym_penalty;
unsigned int combined_tq;
int tq_iface_penalty;
unsigned int tq_iface_penalty;
bool ret = false;
/* find corresponding one hop neighbor */