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wifi: mac80211: fix integer overflow in hwmp_route_info_get()

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Since the new_metric and last_hop_metric variables can reach
the MAX_METRIC(0xffffffff) value, an integer overflow may occur
when multiplying them by 10/9. It can lead to incorrect behavior.

Found by InfoTeCS on behalf of Linux Verification Center
(linuxtesting.org) with SVACE.

Fixes: a8d418d9ac ("mac80211: mesh: only switch path when new metric is at least 10% better")
Cc: stable@vger.kernel.org
Signed-off-by: Ilia Gavrilov <Ilia.Gavrilov@infotecs.ru>
Link: https://patch.msgid.link/20250212082124.4078236-1-Ilia.Gavrilov@infotecs.ru
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Gavrilov Ilia 2025-02-12 08:21:25 +00:00 • committed by Johannes Berg
parent ebf9944bed
commit d00c0c4105
1 changed files with 10 additions and 4 deletions
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14
net/mac80211/mesh_hwmp.c
View file

@ -367,6 +367,12 @@ u32 airtime_link_metric_get(struct ieee80211_local *local,
return (u32)result; return (u32)result;
} }
/* Check that the first metric is at least 10% better than the second one */
static bool is_metric_better(u32 x, u32 y)
{
return (x < y) && (x < (y - x / 10));
}
/** /**
* hwmp_route_info_get - Update routing info to originator and transmitter * hwmp_route_info_get - Update routing info to originator and transmitter
* *
@ -458,8 +464,8 @@ static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
(mpath->sn == orig_sn && (mpath->sn == orig_sn &&
(rcu_access_pointer(mpath->next_hop) != (rcu_access_pointer(mpath->next_hop) !=
sta ? sta ?
mult_frac(new_metric, 10, 9) : !is_metric_better(new_metric, mpath->metric) :
new_metric) >= mpath->metric)) { new_metric >= mpath->metric))) {
process = false; process = false;
fresh_info = false; fresh_info = false;
} }
@ -533,8 +539,8 @@ static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
if ((mpath->flags & MESH_PATH_FIXED) || if ((mpath->flags & MESH_PATH_FIXED) ||
((mpath->flags & MESH_PATH_ACTIVE) && ((mpath->flags & MESH_PATH_ACTIVE) &&
((rcu_access_pointer(mpath->next_hop) != sta ? ((rcu_access_pointer(mpath->next_hop) != sta ?
mult_frac(last_hop_metric, 10, 9) : !is_metric_better(last_hop_metric, mpath->metric) :
last_hop_metric) > mpath->metric))) last_hop_metric > mpath->metric))))
fresh_info = false; fresh_info = false;
} else { } else {
mpath = mesh_path_add(sdata, ta); mpath = mesh_path_add(sdata, ta);