From 01bb11ad828b320749764fa93ad078db20d08a9e Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Thu, 16 Feb 2023 17:39:08 -0800 Subject: sched/topology: fix KASAN warning in hop_cmp() Despite that prev_hop is used conditionally on cur_hop is not the first hop, it's initialized unconditionally. Because initialization implies dereferencing, it might happen that the code dereferences uninitialized memory, which has been spotted by KASAN. Fix it by reorganizing hop_cmp() logic. Reported-by: Bruno Goncalves Fixes: cd7f55359c90 ("sched: add sched_numa_find_nth_cpu()") Signed-off-by: Yury Norov Link: https://lore.kernel.org/r/Y+7avK6V9SyAWsXi@yury-laptop/ Signed-off-by: Jakub Kicinski --- kernel/sched/topology.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 1233affc106c6b..1a9ee8fcd47751 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -2079,14 +2079,19 @@ struct __cmp_key { static int hop_cmp(const void *a, const void *b) { - struct cpumask **prev_hop = *((struct cpumask ***)b - 1); - struct cpumask **cur_hop = *(struct cpumask ***)b; + struct cpumask **prev_hop, **cur_hop = *(struct cpumask ***)b; struct __cmp_key *k = (struct __cmp_key *)a; if (cpumask_weight_and(k->cpus, cur_hop[k->node]) <= k->cpu) return 1; - k->w = (b == k->masks) ? 0 : cpumask_weight_and(k->cpus, prev_hop[k->node]); + if (b == k->masks) { + k->w = 0; + return 0; + } + + prev_hop = *((struct cpumask ***)b - 1); + k->w = cpumask_weight_and(k->cpus, prev_hop[k->node]); if (k->w <= k->cpu) return 0; -- cgit 1.2.3-korg