DivestOS/Patches/Linux_CVEs/CVE-2016-9120/ANY/1.patch

From e9fde8664651a566df43c7439e27d59cc5d60460 Mon Sep 17 00:00:00 2001
From: Daniel Rosenberg <drosen@google.com>
Date: Wed, 2 Nov 2016 17:43:51 -0700
Subject: [PATCH] ion: Fix use after free during ION_IOC_ALLOC

If a user happens to call ION_IOC_FREE during an
ION_IOC_ALLOC on the just allocated id, and the
copy_to_user fails, the cleanup code will attempt
to free an already freed handle.

This adds a wrapper for ion_alloc that adds an
ion_handle_get to avoid this.

Bug: 31568617
Change-Id: I476e5bd5372b5178a213f1fea143d270cf9361ed
Signed-off-by: Daniel Rosenberg <drosen@google.com>
---
 drivers/staging/android/ion/ion.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index 8bbbb38dc7c41..63e6b7d795f47 100755
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -507,9 +507,9 @@ static int ion_handle_add(struct ion_client *client, struct ion_handle *handle)
 	return 0;
 }
 
-struct ion_handle *ion_alloc(struct ion_client *client, size_t len,
+static struct ion_handle *__ion_alloc(struct ion_client *client, size_t len,
 			     size_t align, unsigned int heap_id_mask,
-			     unsigned int flags)
+			     unsigned int flags, bool grab_handle)
 {
 	struct ion_handle *handle;
 	struct ion_device *dev = client->dev;
@@ -604,6 +604,8 @@ struct ion_handle *ion_alloc(struct ion_client *client, size_t len,
 		return handle;
 
 	mutex_lock(&client->lock);
+	if (grab_handle)
+		ion_handle_get(handle);
 	ret = ion_handle_add(client, handle);
 	mutex_unlock(&client->lock);
 	if (ret) {
@@ -613,6 +615,13 @@ struct ion_handle *ion_alloc(struct ion_client *client, size_t len,
 
 	return handle;
 }
+
+struct ion_handle *ion_alloc(struct ion_client *client, size_t len,
+			     size_t align, unsigned int heap_id_mask,
+			     unsigned int flags)
+{
+	return __ion_alloc(client, len, align, heap_id_mask, flags, false);
+}
 EXPORT_SYMBOL(ion_alloc);
 
 static void ion_free_nolock(struct ion_client *client, struct ion_handle *handle)
@@ -1488,10 +1497,10 @@ static long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	{
 		struct ion_handle *handle;
 
-		handle = ion_alloc(client, data.allocation.len,
+		handle = __ion_alloc(client, data.allocation.len,
 						data.allocation.align,
 						data.allocation.heap_id_mask,
-						data.allocation.flags);
+						data.allocation.flags, true);
 		if (IS_ERR(handle))
 			return PTR_ERR(handle);
 
@@ -1568,11 +1577,15 @@ static long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 
 	if (dir & _IOC_READ) {
 		if (copy_to_user((void __user *)arg, &data, _IOC_SIZE(cmd))) {
-			if (cleanup_handle)
+			if (cleanup_handle) {
 				ion_free(client, cleanup_handle);
+				ion_handle_put(cleanup_handle);
+			}
 			return -EFAULT;
 		}
 	}
+	if (cleanup_handle)
+		ion_handle_put(cleanup_handle);
 	return ret;
 }