From nobody Tue Sep 9 21:28:39 2025 Received: from out-178.mta0.migadu.com (out-178.mta0.migadu.com [91.218.175.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 404B5322539 for ; Fri, 5 Sep 2025 11:03:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.178 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757070193; cv=none; b=a8jIwoFOCpwry+3IdT0oJdzV7A5rQi8OYahrWQSYzjDOSwmETeexZh0P7aHDt+RYSPhzj5z23+nwaBhQX3OX3FJRYWIqGJik98cts1sNs/KYA9l/onVSkQxld1KucMUeHZeUD3ovQFTxQ3EtpzvYAlE9TOEzihwosu9z5TJrML8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757070193; c=relaxed/simple; bh=tGiTIgxzfL0ZubePlSyKKw5/M+qMw+lnVwvCXioNp8o=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=msZ+4YBbCku/MAsaX4Ji4HfqGWiufPbWt13BV2l2xQR6PhGM/1mBs+NS3tqXOVgvOHp4u16n6zigqiCEhwnIuQHMwrRivZHfVHTMKkR67Pd3PsTnNRoqrKaA1/wJjrzH7eZyxwPn/J1tuJxg7Kv7saL6tex1prFd8ZVNWUKLUVc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=jJB4KL6O; arc=none smtp.client-ip=91.218.175.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="jJB4KL6O" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1757070188; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=jU0V2LUx2VEIKkr5+zOng1DSdA2xbaRRNLzM6WgBwNk=; b=jJB4KL6On/uo/T/IUOcrWMuRYlRqrV4fGT2EtF8V8yB0rF3VlpYDSo4pRrz5gZMb9HJRhu WKbs8alWW12fMIEvBNCx6UDuNZe9SrpwKv+W/WQgOlEjFIqwwiXuWJfd9jyWu/59XM4rWp 9FXFOHCmhO296R6htqJ+UYS8IHciEwE= From: Thorsten Blum To: Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Jan Kara , Thorsten Blum , Christian Brauner , Jeff Layton Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] s390/hmcdrv: Replace kmalloc() + copy_from_user() with memdup_user_nul() Date: Fri, 5 Sep 2025 13:02:23 +0200 Message-ID: <20250905110226.485009-2-thorsten.blum@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" Replace kmalloc() followed by copy_from_user() with memdup_user_nul() to improve and simplify hmcdrv_dev_write(). Remove the manual NUL-termination. No functional changes intended. Signed-off-by: Thorsten Blum --- drivers/s390/char/hmcdrv_dev.c | 19 ++++++------------- 1 file changed, 6 insertions(+), 13 deletions(-) diff --git a/drivers/s390/char/hmcdrv_dev.c b/drivers/s390/char/hmcdrv_dev.c index e069dd685899..b26fcf6849f2 100644 --- a/drivers/s390/char/hmcdrv_dev.c +++ b/drivers/s390/char/hmcdrv_dev.c @@ -244,24 +244,17 @@ static ssize_t hmcdrv_dev_write(struct file *fp, cons= t char __user *ubuf, size_t len, loff_t *pos) { ssize_t retlen; + void *pdata; =20 pr_debug("writing file '/dev/%pD' at pos. %lld with length %zd\n", fp, (long long) *pos, len); =20 if (!fp->private_data) { /* first expect a cmd write */ - fp->private_data =3D kmalloc(len + 1, GFP_KERNEL); - - if (!fp->private_data) - return -ENOMEM; - - if (!copy_from_user(fp->private_data, ubuf, len)) { - ((char *)fp->private_data)[len] =3D '\0'; - return len; - } - - kfree(fp->private_data); - fp->private_data =3D NULL; - return -EFAULT; + pdata =3D memdup_user_nul(ubuf, len); + if (IS_ERR(pdata)) + return PTR_ERR(pdata); + fp->private_data =3D pdata; + return len; } =20 retlen =3D hmcdrv_dev_transfer((char *) fp->private_data, --=20 2.51.0