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From:   Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        linux-kernel@vger.kernel.org
Cc:     Luis Chamberlain <mcgrof@kernel.org>
Subject: [PATCH v1 3/6] params: Do not go over the limit when getting the string length
Date:   Tue, 12 Sep 2023 18:05:48 +0300
Message-Id: <20230912150551.401537-3-andriy.shevchenko@linux.intel.com>
In-Reply-To: <20230912150551.401537-1-andriy.shevchenko@linux.intel.com>
References: <20230912150551.401537-1-andriy.shevchenko@linux.intel.com>
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We can use strnlen() even on early stages and it prevents from
going over the string boundaries in case it's already too long.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 kernel/params.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/params.c b/kernel/params.c
index fb594132ffc7..930a5dc2f004 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -259,7 +259,10 @@ EXPORT_SYMBOL_GPL(param_set_uint_minmax);
 
 int param_set_charp(const char *val, const struct kernel_param *kp)
 {
-	if (strlen(val) > 1024) {
+	size_t len, maxlen = 1024;
+
+	len = strnlen(val, maxlen + 1);
+	if (len == maxlen + 1) {
 		pr_err("%s: string parameter too long\n", kp->name);
 		return -ENOSPC;
 	}
@@ -269,7 +272,7 @@ int param_set_charp(const char *val, const struct kernel_param *kp)
 	/* This is a hack.  We can't kmalloc in early boot, and we
 	 * don't need to; this mangled commandline is preserved. */
 	if (slab_is_available()) {
-		*(char **)kp->arg = kmalloc_parameter(strlen(val)+1);
+		*(char **)kp->arg = kmalloc_parameter(len + 1);
 		if (!*(char **)kp->arg)
 			return -ENOMEM;
 		strcpy(*(char **)kp->arg, val);
@@ -507,7 +510,7 @@ int param_set_copystring(const char *val, const struct kernel_param *kp)
 {
 	const struct kparam_string *kps = kp->str;
 
-	if (strlen(val)+1 > kps->maxlen) {
+	if (strnlen(val, kps->maxlen) == kps->maxlen) {
 		pr_err("%s: string doesn't fit in %u chars.\n",
 		       kp->name, kps->maxlen-1);
 		return -ENOSPC;
-- 
2.40.0.1.gaa8946217a0b