linux-kernel - [PATCH v2] lkdtm/bugs: Check for the NULL pointer after calling kmalloc

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Message-Id: <20220119122055.1826561-1-jiasheng@iscas.ac.cn>
Date:   Wed, 19 Jan 2022 20:20:55 +0800
From:   Jiasheng Jiang <jiasheng@...as.ac.cn>
To:     dan.carpenter@...cle.com, keescook@...omium.org, arnd@...db.de,
        gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org, Jiasheng Jiang <jiasheng@...as.ac.cn>
Subject: [PATCH v2] lkdtm/bugs: Check for the NULL pointer after calling kmalloc

As the possible failure of the kmalloc(), the not_checked and checked
could be NULL pointer.
Therefore, it should be better to check it in order to avoid the
dereference of the NULL pointer.
Also, we need to kfree the 'not_checked' and 'checked' to avoid
the memory leak if fails.
And since it is just a test, it may directly return without error
number.

Fixes: ae2e1aad3e48 ("drivers/misc/lkdtm/bugs.c: add arithmetic overflow and array bounds checks")
Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
---
Changelog

v1 -> v2

* Change 1. Add the kfree if fails.
---
 drivers/misc/lkdtm/bugs.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c
index f4cb94a9aa9c..c35ea54824ac 100644
--- a/drivers/misc/lkdtm/bugs.c
+++ b/drivers/misc/lkdtm/bugs.c
@@ -325,6 +325,11 @@ void lkdtm_ARRAY_BOUNDS(void)
 
 	not_checked = kmalloc(sizeof(*not_checked) * 2, GFP_KERNEL);
 	checked = kmalloc(sizeof(*checked) * 2, GFP_KERNEL);
+	if (!not_checked || !checked) {
+		kfree(not_checked);
+		kfree(checked);
+		return;
+	}
 
 	pr_info("Array access within bounds ...\n");
 	/* For both, touch all bytes in the actual member size. */
-- 
2.25.1