5.4-stable review patch. If anyone has any objections, please let me know.
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From: Gavrilov Ilia Ilia.Gavrilov@infotecs.ru
commit d00c0c4105e5ab8a6a13ed23d701cceb285761fa upstream.
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: a8d418d9ac25 ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/mac80211/mesh_hwmp.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-)
--- a/net/mac80211/mesh_hwmp.c +++ b/net/mac80211/mesh_hwmp.c @@ -360,6 +360,12 @@ u32 airtime_link_metric_get(struct ieee8 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 * @@ -450,8 +456,8 @@ static u32 hwmp_route_info_get(struct ie (mpath->sn == orig_sn && (rcu_access_pointer(mpath->next_hop) != sta ? - mult_frac(new_metric, 10, 9) : - new_metric) >= mpath->metric)) { + !is_metric_better(new_metric, mpath->metric) : + new_metric >= mpath->metric))) { process = false; fresh_info = false; } @@ -521,8 +527,8 @@ static u32 hwmp_route_info_get(struct ie if ((mpath->flags & MESH_PATH_FIXED) || ((mpath->flags & MESH_PATH_ACTIVE) && ((rcu_access_pointer(mpath->next_hop) != sta ? - mult_frac(last_hop_metric, 10, 9) : - last_hop_metric) > mpath->metric))) + !is_metric_better(last_hop_metric, mpath->metric) : + last_hop_metric > mpath->metric)))) fresh_info = false; } else { mpath = mesh_path_add(sdata, ta);