Commit 571a9637 authored by Ruben Wisniewski's avatar Ruben Wisniewski Committed by Antonio Quartulli

batman-adv: Avoid u32 overflow during gateway select

The gateway selection based on fast connections is using a single value
calculated from the average tq (0-255) and the download bandwidth (in
100Kibit). The formula for the first step (tq ** 2 * 10000 * bandwidth)
tends to overflow a u32 with low bandwidth settings like 50 [100KiBit]
and a tq value of over 92.

Changing this to a 64 bit unsigned integer allows to support a
bandwidth_down with up to ~2.8e10 [100KiBit] and a perfect tq of 255. This
is ~6.6 times higher than the maximum possible value of the gateway
announcement TVLV.

This problem only affects the non-default gw_sel_class 1.
Signed-off-by: default avatarRuben Wisniewsi <ruben@vfn-nrw.de>
[sven@narfation.org: rewritten commit message]
Signed-off-by: default avatarSven Eckelmann <sven@narfation.org>
Signed-off-by: default avatarMarek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: default avatarAntonio Quartulli <antonio@meshcoding.com>
parent e071d93e
...@@ -153,7 +153,7 @@ batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv) ...@@ -153,7 +153,7 @@ batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv)
struct batadv_neigh_node *router; struct batadv_neigh_node *router;
struct batadv_neigh_ifinfo *router_ifinfo; struct batadv_neigh_ifinfo *router_ifinfo;
struct batadv_gw_node *gw_node, *curr_gw = NULL; struct batadv_gw_node *gw_node, *curr_gw = NULL;
uint32_t max_gw_factor = 0, tmp_gw_factor = 0; uint64_t max_gw_factor = 0, tmp_gw_factor = 0;
uint8_t max_tq = 0; uint8_t max_tq = 0;
uint8_t tq_avg; uint8_t tq_avg;
struct batadv_orig_node *orig_node; struct batadv_orig_node *orig_node;
......
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