linux-kernel - [PATCH] lkdtm: use the return value of strim()

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Message-Id: <20230817142117.972418-1-gongruiqi@huaweicloud.com>
Date:   Thu, 17 Aug 2023 22:21:17 +0800
From:   "GONG, Ruiqi" <gongruiqi@...weicloud.com>
To:     Kees Cook <keescook@...omium.org>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Cc:     gongruiqi1@...wei.com
Subject: [PATCH] lkdtm: use the return value of strim()

From: "GONG, Ruiqi" <gongruiqi1@...wei.com>

Make use of the return value of strim() to achieve left-trim as well as
right-trim, which prevents the following unusual fail case:

 # echo " EXCEPTION" > /sys/kernel/debug/provoke-crash/DIRECT
 sh: write error: Invalid argument

Link: https://github.com/KSPP/linux/issues/337
Signed-off-by: GONG, Ruiqi <gongruiqi1@...wei.com>
---
 drivers/misc/lkdtm/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
index 0772e4a4757e..812c96461ab2 100644
--- a/drivers/misc/lkdtm/core.c
+++ b/drivers/misc/lkdtm/core.c
@@ -242,7 +242,7 @@ static ssize_t lkdtm_debugfs_entry(struct file *f,
 	}
 	/* NULL-terminate and remove enter */
 	buf[count] = '\0';
-	strim(buf);
+	buf = strim(buf);
 
 	crashtype = find_crashtype(buf);
 	free_page((unsigned long)buf);
@@ -318,7 +318,7 @@ static ssize_t direct_entry(struct file *f, const char __user *user_buf,
 	}
 	/* NULL-terminate and remove enter */
 	buf[count] = '\0';
-	strim(buf);
+	buf = strim(buf);
 
 	crashtype = find_crashtype(buf);
 	free_page((unsigned long) buf);
-- 
2.25.1