From: Yury Norov Date: Fri, 17 Feb 2023 01:39:08 +0000 (-0800) Subject: sched/topology: fix KASAN warning in hop_cmp() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=01bb11ad828b320749764fa93ad078db20d08a9e;p=linux.git 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 --- diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 1233affc106c6..1a9ee8fcd4775 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;