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From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Luis Chamberlain <mcgrof@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: [PATCH v2 2/5] params: Do not go over the limit when getting the string length
Date: Mon,  2 Oct 2023 15:48:53 +0300	[thread overview]
Message-ID: <20231002124856.2455696-3-andriy.shevchenko@linux.intel.com> (raw)
In-Reply-To: <20231002124856.2455696-1-andriy.shevchenko@linux.intel.com>

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 626fa8265932..f8e3c4139854 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -260,7 +260,10 @@ 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;
 	}
@@ -270,7 +273,7 @@ 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);
@@ -508,7 +511,7 @@ 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


  parent reply	other threads:[~2023-10-02 12:49 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-02 12:48 [PATCH v2 0/5] params: harden string ops and allocatio ops Andy Shevchenko
2023-10-02 12:48 ` [PATCH v2 1/5] params: Introduce the param_unknown_fn type Andy Shevchenko
2023-10-02 12:48 ` Andy Shevchenko [this message]
2023-10-02 16:57   ` [PATCH v2 2/5] params: Do not go over the limit when getting the string length Kees Cook
2023-10-02 12:48 ` [PATCH v2 3/5] params: Use size_add() for kmalloc() Andy Shevchenko
2023-10-02 12:48 ` [PATCH v2 4/5] params: Sort headers Andy Shevchenko
2023-10-02 12:48 ` [PATCH v2 5/5] params: Fix multi-line comment style Andy Shevchenko
2023-10-02 16:57 ` [PATCH v2 0/5] params: harden string ops and allocatio ops Kees Cook
2023-10-10 23:21   ` Luis Chamberlain

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