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Date: Wed, 2 Mar 2016 21:58:56 -0800
From: Gwendal Grignou <gwendal@...omium.org>
To: olofj@...omium.org, alan@...rguk.ukuu.org.uk,
javier.martinez@...labora.co.uk
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH] platform/chrome: cros_ec_dev - Fix security issue
Add a check to prevent memory scribbe when sending an ioctl with .insize
set so large that memory allocation argument overflows.
Signed-off-by: Gwendal Grignou <gwendal@...omium.org>
---
drivers/platform/chrome/cros_ec_dev.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/platform/chrome/cros_ec_dev.c b/drivers/platform/chrome/cros_ec_dev.c
index d45cd25..86d6373 100644
--- a/drivers/platform/chrome/cros_ec_dev.c
+++ b/drivers/platform/chrome/cros_ec_dev.c
@@ -131,13 +131,23 @@ static ssize_t ec_device_read(struct file *filp, char __user *buffer,
static long ec_device_ioctl_xcmd(struct cros_ec_dev *ec, void __user *arg)
{
long ret;
+ size_t data_size;
struct cros_ec_command u_cmd;
struct cros_ec_command *s_cmd;
if (copy_from_user(&u_cmd, arg, sizeof(u_cmd)))
return -EFAULT;
- s_cmd = kmalloc(sizeof(*s_cmd) + max(u_cmd.outsize, u_cmd.insize),
+ /*
+ * Prevent mallicious attack where .inside is so big that amount
+ * kmalloc'ed rollover, allowing memcpy to write beyond the allocated
+ * space.
+ */
+ data_size = max(u_cmd.outsize, u_cmd.insize);
+ if (data_size + sizeof(*s_cmd) < data_size)
+ return -EINVAL;
+
+ s_cmd = kmalloc(sizeof(*s_cmd) + data_size,
GFP_KERNEL);
if (!s_cmd)
return -ENOMEM;
--
2.7.0.rc3.207.g0ac5344
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