linux-kernel - [PATCH v2] platform/x86/amd/pmf: Use memdup

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Date: Mon, 27 May 2024 10:36:29 +0200
From: Thorsten Blum <thorsten.blum@...lux.com>
To: markus.elfring@....de
Cc: Shyam-sundar.S-k@....com,
	hdegoede@...hat.com,
	ilpo.jarvinen@...ux.intel.com,
	kernel-janitors@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	platform-driver-x86@...r.kernel.org,
	thorsten.blum@...lux.com
Subject: [PATCH v2] platform/x86/amd/pmf: Use memdup_user()

Switch to memdup_user() to overwrite the allocated memory only once
instead of initializing the allocated memory to zero with kzalloc() and
then immediately overwriting it with copy_from_user().

Fix the following Coccinelle/coccicheck warning reported by
memdup_user.cocci:

	WARNING opportunity for memdup_user

Signed-off-by: Thorsten Blum <thorsten.blum@...lux.com>
---
Changes in v2:
- Update patch description after feedback from Markus Elfring
---
 drivers/platform/x86/amd/pmf/tee-if.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/drivers/platform/x86/amd/pmf/tee-if.c b/drivers/platform/x86/amd/pmf/tee-if.c
index b438de4d6bfc..1b53cabc9aa2 100644
--- a/drivers/platform/x86/amd/pmf/tee-if.c
+++ b/drivers/platform/x86/amd/pmf/tee-if.c
@@ -301,14 +301,9 @@ static ssize_t amd_pmf_get_pb_data(struct file *filp, const char __user *buf,
 		return -EINVAL;
 
 	/* re-alloc to the new buffer length of the policy binary */
-	new_policy_buf = kzalloc(length, GFP_KERNEL);
-	if (!new_policy_buf)
-		return -ENOMEM;
-
-	if (copy_from_user(new_policy_buf, buf, length)) {
-		kfree(new_policy_buf);
-		return -EFAULT;
-	}
+	new_policy_buf = memdup_user(buf, length);
+	if (IS_ERR(new_policy_buf))
+		return PTR_ERR(new_policy_buf);
 
 	kfree(dev->policy_buf);
 	dev->policy_buf = new_policy_buf;
-- 
2.45.1