linux-kernel - [PATCH] drm/i915: use memdup_user

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Message-Id: <6baf3aa45d0b5e0fd016b508bac905ebf8443aac.1493779294.git.geliangtang@gmail.com>
Date:   Sat,  6 May 2017 23:40:17 +0800
From:   Geliang Tang <geliangtang@...il.com>
To:     Daniel Vetter <daniel.vetter@...el.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        David Airlie <airlied@...ux.ie>
Cc:     Geliang Tang <geliangtang@...il.com>,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] drm/i915: use memdup_user_nul

Use memdup_user_nul() helper instead of open-coding to simplify the
code.

Signed-off-by: Geliang Tang <geliangtang@...il.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c   | 13 +++----------
 drivers/gpu/drm/i915/intel_pipe_crc.c | 13 +++----------
 2 files changed, 6 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index d689e51..e56b636 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -3704,16 +3704,10 @@ static ssize_t i915_displayport_test_active_write(struct file *file,
 	if (len == 0)
 		return 0;
 
-	input_buffer = kmalloc(len + 1, GFP_KERNEL);
-	if (!input_buffer)
-		return -ENOMEM;
+	input_buffer = memdup_user_nul(ubuf, len);
+	if (IS_ERR(input_buffer))
+		return PTR_ERR(input_buffer);
 
-	if (copy_from_user(input_buffer, ubuf, len)) {
-		status = -EFAULT;
-		goto out;
-	}
-
-	input_buffer[len] = '\0';
 	DRM_DEBUG_DRIVER("Copied %d bytes from user\n", (unsigned int)len);
 
 	drm_connector_list_iter_begin(dev, &conn_iter);
@@ -3739,7 +3733,6 @@ static ssize_t i915_displayport_test_active_write(struct file *file,
 		}
 	}
 	drm_connector_list_iter_end(&conn_iter);
-out:
 	kfree(input_buffer);
 	if (status < 0)
 		return status;
diff --git a/drivers/gpu/drm/i915/intel_pipe_crc.c b/drivers/gpu/drm/i915/intel_pipe_crc.c
index 206ee4f..813dd3c 100644
--- a/drivers/gpu/drm/i915/intel_pipe_crc.c
+++ b/drivers/gpu/drm/i915/intel_pipe_crc.c
@@ -842,19 +842,12 @@ static ssize_t display_crc_ctl_write(struct file *file, const char __user *ubuf,
 		return -E2BIG;
 	}
 
-	tmpbuf = kmalloc(len + 1, GFP_KERNEL);
-	if (!tmpbuf)
-		return -ENOMEM;
-
-	if (copy_from_user(tmpbuf, ubuf, len)) {
-		ret = -EFAULT;
-		goto out;
-	}
-	tmpbuf[len] = '\0';
+	tmpbuf = memdup_user_nul(ubuf, len);
+	if (IS_ERR(tmpbuf))
+		return PTR_ERR(tmpbuf);
 
 	ret = display_crc_ctl_parse(dev_priv, tmpbuf, len);
 
-out:
 	kfree(tmpbuf);
 	if (ret < 0)
 		return ret;
-- 
2.9.3