mirror of
https://github.com/Divested-Mobile/DivestOS-Build.git
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68 lines
2.0 KiB
Diff
68 lines
2.0 KiB
Diff
From 03c26a1d8c8687131da151c2e4bd5a04d08e0dec Mon Sep 17 00:00:00 2001
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From: Ariel Yin <ayin@google.com>
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Date: Fri, 13 Jan 2017 15:05:54 -0800
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Subject: [PATCH] ANDROID: ion: check for kref overflow
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Userspace can cause the kref to handles to increment
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arbitrarily high. Ensure it does not overflow.
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Signed-off-by: Daniel Rosenberg <drosen@google.com>
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Bug: 31992382
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Test: See bug for poc
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Change-Id: I6bff1df385742b1d836d43180dc87fadcea80782
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---
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drivers/staging/android/ion/ion.c | 17 ++++++++++++++---
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1 file changed, 14 insertions(+), 3 deletions(-)
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diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
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index cc1b3bff392ac..48b6b86a61945 100644
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--- a/drivers/staging/android/ion/ion.c
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+++ b/drivers/staging/android/ion/ion.c
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@@ -16,6 +16,8 @@
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*
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*/
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+#include <linux/atomic.h>
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+#include <linux/err.h>
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#include <linux/file.h>
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#include <linux/freezer.h>
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#include <linux/fs.h>
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@@ -400,6 +402,15 @@ static void ion_handle_get(struct ion_handle *handle)
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kref_get(&handle->ref);
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}
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+/* Must hold the client lock */
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+static struct ion_handle* ion_handle_get_check_overflow(struct ion_handle *handle)
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+{
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+ if (atomic_read(&handle->ref.refcount) + 1 == 0)
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+ return ERR_PTR(-EOVERFLOW);
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+ ion_handle_get(handle);
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+ return handle;
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+}
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+
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int ion_handle_put_nolock(struct ion_handle *handle)
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{
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int ret;
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@@ -445,9 +456,9 @@ struct ion_handle *ion_handle_get_by_id_nolock(struct ion_client *client,
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handle = idr_find(&client->idr, id);
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if (handle)
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- ion_handle_get(handle);
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+ return ion_handle_get_check_overflow(handle);
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- return handle ? handle : ERR_PTR(-EINVAL);
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+ return ERR_PTR(-EINVAL);
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}
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struct ion_handle *ion_handle_get_by_id(struct ion_client *client,
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@@ -1339,7 +1350,7 @@ struct ion_handle *ion_import_dma_buf(struct ion_client *client, int fd)
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/* if a handle exists for this buffer just take a reference to it */
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handle = ion_handle_lookup(client, buffer);
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if (!IS_ERR(handle)) {
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- ion_handle_get(handle);
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+ handle = ion_handle_get_check_overflow(handle);
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mutex_unlock(&client->lock);
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goto end;
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}
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