linux-kernel - [PATCH RESEND 1/2] stm class: Replace kmalloc + copy_from_user with memdup

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Message-ID: <20251017102743.75394-2-thorsten.blum@linux.dev>
Date: Fri, 17 Oct 2025 12:27:42 +0200
From: Thorsten Blum <thorsten.blum@...ux.dev>
To: Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>
Cc: Thorsten Blum <thorsten.blum@...ux.dev>,
	linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH RESEND 1/2] stm class: Replace kmalloc + copy_from_user with memdup_user

Replace kmalloc() followed by copy_from_user() with memdup_user() to
simplify and improve stm_char_write().

Allocate and copy only 'count' bytes instead of 'count + 1' since the
extra byte is unused.

Signed-off-by: Thorsten Blum <thorsten.blum@...ux.dev>
---
 drivers/hwtracing/stm/core.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index cdba4e875b28..5834f796e86b 100644
--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -645,15 +645,9 @@ static ssize_t stm_char_write(struct file *file, const char __user *buf,
 			return err;
 	}
 
-	kbuf = kmalloc(count + 1, GFP_KERNEL);
-	if (!kbuf)
-		return -ENOMEM;
-
-	err = copy_from_user(kbuf, buf, count);
-	if (err) {
-		kfree(kbuf);
-		return -EFAULT;
-	}
+	kbuf = memdup_user(buf, count);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
 
 	pm_runtime_get_sync(&stm->dev);
 
-- 
2.51.0