linux-kernel - [PATCH] i2c: dev: zero out array used for i2c reads from userspace

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Message-Id: <20210729102443.1729100-1-gregkh@linuxfoundation.org>
Date:   Thu, 29 Jul 2021 12:24:43 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Wolfram Sang <wsa@...nel.org>, linux-i2c@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH] i2c: dev: zero out array used for i2c reads from userspace

If an i2c driver happens to not provide the full amount of data that a
user asks for, it is possible that some uninitialized data could be sent
to userspace.  While all in-kernel drivers look to be safe, just be sure
by initializing the buffer to zero before it is passed to the i2c driver
so that any future drivers will not have this issue.

Reported-by: Eric Dumazet <edumazet@...gle.com>
Cc: Wolfram Sang <wsa@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/i2c/i2c-dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index cb64fe649390..ae59ef5748f4 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -141,7 +141,7 @@ static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count,
 	if (count > 8192)
 		count = 8192;
 
-	tmp = kmalloc(count, GFP_KERNEL);
+	tmp = kzalloc(count, GFP_KERNEL);
 	if (tmp == NULL)
 		return -ENOMEM;
 
-- 
2.32.0