linux-kernel - [PATCH v1] sched/fair: Fix memory leak in alloc_fair_sched

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Message-Id: <20250623061909.13480-1-zhangzihuan@kylinos.cn>
Date: Mon, 23 Jun 2025 14:19:09 +0800
From: Zihuan Zhang <zhangzihuan@...inos.cn>
To: mingo@...hat.com,
	peterz@...radead.org,
	juri.lelli@...hat.com,
	vincent.guittot@...aro.org,
	dietmar.eggemann@....com,
	rostedt@...dmis.org,
	bsegall@...gle.com,
	mgorman@...e.de,
	vschneid@...hat.com
Cc: linux-kernel@...r.kernel.org,
	Zihuan Zhang <zhangzihuan@...inos.cn>
Subject: [PATCH v1] sched/fair: Fix memory leak in alloc_fair_sched_group()

alloc_fair_sched_group() allocates per-CPU cfs_rq[] and se[] arrays
for a task group. However, if either allocation fails, or a per-CPU
allocation fails during the loop, the function may leak memory.
This patch fixes the memory leak by:
- Using sizeof(*ptr) instead of sizeof(ptr) for correctness.
- Using the existing free_fair_sched_group() function to clean up
Note: Calling free_fair_sched_group() unconditionally in the failure
path is safe, as kfree(NULL) is a no-op in the kernel. This avoids
duplicating cleanup logic and improves robustness.

Signed-off-by: Zihuan Zhang <zhangzihuan@...inos.cn>
---
 kernel/sched/fair.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7a14da5396fb..920174245517 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -13372,12 +13372,12 @@ int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
 	struct cfs_rq *cfs_rq;
 	int i;
 
-	tg->cfs_rq = kcalloc(nr_cpu_ids, sizeof(cfs_rq), GFP_KERNEL);
+	tg->cfs_rq = kcalloc(nr_cpu_ids, sizeof(*tg->cfs_rq), GFP_KERNEL);
 	if (!tg->cfs_rq)
 		goto err;
-	tg->se = kcalloc(nr_cpu_ids, sizeof(se), GFP_KERNEL);
+	tg->se = kcalloc(nr_cpu_ids, sizeof(*tg->se), GFP_KERNEL);
 	if (!tg->se)
-		goto err;
+		goto err_free_rq;
 
 	tg->shares = NICE_0_LOAD;
 
@@ -13387,7 +13387,7 @@ int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
 		cfs_rq = kzalloc_node(sizeof(struct cfs_rq),
 				      GFP_KERNEL, cpu_to_node(i));
 		if (!cfs_rq)
-			goto err;
+			goto err_free_rq;
 
 		se = kzalloc_node(sizeof(struct sched_entity_stats),
 				  GFP_KERNEL, cpu_to_node(i));
@@ -13402,7 +13402,7 @@ int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
 	return 1;
 
 err_free_rq:
-	kfree(cfs_rq);
+	free_fair_sched_group(tg);
 err:
 	return 0;
 }
-- 
2.25.1