linux-kernel - [PATCH] mm/page_alloc.c: fix early params garbage value accesses

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Date:   Wed, 16 Sep 2020 23:41:25 +0200
From:   mateusznosek0@...il.com
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     Mateusz Nosek <mateusznosek0@...il.com>, akpm@...ux-foundation.org
Subject: [PATCH] mm/page_alloc.c: fix early params garbage value accesses

From: Mateusz Nosek <mateusznosek0@...il.com>

Previously in '__init early_init_on_alloc' and '__init early_init_on_free'
the return values from 'kstrtobool' were not handled properly. That caused
potential garbage value read from variable 'bool_result'. Introduced patch
fixes error handling.

Signed-off-by: Mateusz Nosek <mateusznosek0@...il.com>
---
 mm/page_alloc.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6b699d273d6e..112e5a63f9ca 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -155,16 +155,16 @@ static int __init early_init_on_alloc(char *buf)
 	int ret;
 	bool bool_result;
 
-	if (!buf)
-		return -EINVAL;
 	ret = kstrtobool(buf, &bool_result);
+	if (ret)
+		return ret;
 	if (bool_result && page_poisoning_enabled())
 		pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, will take precedence over init_on_alloc\n");
 	if (bool_result)
 		static_branch_enable(&init_on_alloc);
 	else
 		static_branch_disable(&init_on_alloc);
-	return ret;
+	return 0;
 }
 early_param("init_on_alloc", early_init_on_alloc);
 
@@ -173,16 +173,16 @@ static int __init early_init_on_free(char *buf)
 	int ret;
 	bool bool_result;
 
-	if (!buf)
-		return -EINVAL;
 	ret = kstrtobool(buf, &bool_result);
+	if (ret)
+		return ret;
 	if (bool_result && page_poisoning_enabled())
 		pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, will take precedence over init_on_free\n");
 	if (bool_result)
 		static_branch_enable(&init_on_free);
 	else
 		static_branch_disable(&init_on_free);
-	return ret;
+	return 0;
 }
 early_param("init_on_free", early_init_on_free);
 
-- 
2.20.1