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authorDaniel Rosenberg <drosen@google.com>2018-08-30 16:09:46 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-09-05 09:20:11 +0200
commit3af20bddda6f24b5a1c0072f2f6e3bb3ed04bf78 (patch)
tree801d79540e6ca2c9746c6d4fc27881a91124e53b
parentb8c0e15469bab732065e64f7dffadab0b7103990 (diff)
staging: android: ion: check for kref overflow
This patch is against 4.9. It does not apply to master due to a large rework of ion in 4.12 which removed the affected functions altogther. 4c23cbff073f3b9b ("staging: android: ion: Remove import interface") Userspace can cause the kref to handles to increment arbitrarily high. Ensure it does not overflow. Signed-off-by: Daniel Rosenberg <drosen@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/staging/android/ion/ion.c17
1 files changed, 14 insertions, 3 deletions
diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index 403df8bf4b48..806e9b30b9dc 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -15,6 +15,7 @@
*
*/
+#include <linux/atomic.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/file.h>
@@ -305,6 +306,16 @@ static void ion_handle_get(struct ion_handle *handle)
kref_get(&handle->ref);
}
+/* Must hold the client lock */
+static struct ion_handle *ion_handle_get_check_overflow(
+ struct ion_handle *handle)
+{
+ if (atomic_read(&handle->ref.refcount) + 1 == 0)
+ return ERR_PTR(-EOVERFLOW);
+ ion_handle_get(handle);
+ return handle;
+}
+
int ion_handle_put_nolock(struct ion_handle *handle)
{
return kref_put(&handle->ref, ion_handle_destroy);
@@ -347,9 +358,9 @@ struct ion_handle *ion_handle_get_by_id_nolock(struct ion_client *client,
handle = idr_find(&client->idr, id);
if (handle)
- ion_handle_get(handle);
+ return ion_handle_get_check_overflow(handle);
- return handle ? handle : ERR_PTR(-EINVAL);
+ return ERR_PTR(-EINVAL);
}
static bool ion_handle_validate(struct ion_client *client,
@@ -1110,7 +1121,7 @@ struct ion_handle *ion_import_dma_buf(struct ion_client *client,
/* if a handle exists for this buffer just take a reference to it */
handle = ion_handle_lookup(client, buffer);
if (!IS_ERR(handle)) {
- ion_handle_get(handle);
+ handle = ion_handle_get_check_overflow(handle);
mutex_unlock(&client->lock);
goto end;
}