linux-kernel - [PATCH] input: Null-termination of strings returned to userspace

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Message-Id: <200608022336.30648.wigge@bigfoot.com>
Date:	Wed, 2 Aug 2006 23:36:30 +0200
From:	Magnus Vigerlöf <wigge@...foot.com>
To:	linux-input@...ey.karlin.mff.cuni.cz
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] input: Null-termination of strings returned to userspace

Removes the risk of returning non-null terminated strings
to userspace in those cases the provided buffer is too small.

Signed-off-by: Magnus Vigerlöf <wigge@...foot.com>
---
diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index 12c7ab8..667333c 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -377,11 +377,13 @@ static int str_to_user(const char *str, 
 	if (!str)
 		return -ENOENT;
 
-	len = strlen(str) + 1;
-	if (len > maxlen)
-		len = maxlen;
+	len = strlen(str);
+	if (len >= maxlen)
+		len = maxlen - 1;
 
-	return copy_to_user(p, str, len) ? -EFAULT : len;
+	if (copy_to_user(p, str, len))
+		return -EFAULT;
+	return put_user('\0', (char __user *)p + len) ? -EFAULT : len + 1;
 }
 
 static long evdev_ioctl_handler(struct file *file, unsigned int cmd,
-
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