diff options
| author | Daniel Rosenberg <drosen@google.com> | 2016-12-05 16:28:28 -0800 |
|---|---|---|
| committer | Gerrit - the friendly Code Review server <code-review@localhost> | 2017-03-31 16:37:58 -0700 |
| commit | f6c025297e99d250bdadae98a8544ba7cdcf6993 (patch) | |
| tree | 6aa70894a1bb3cc2bc68c57ec3cf50906a8510ad | |
| parent | 92124c76a2bd3e0c1d98de91d09199558117a1a9 (diff) | |
ANDROID: ion: check for kref overflow
Userspace can cause the kref to handles to increment
arbitrarily high. Ensure it does not overflow.
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Bug: 31992382
Test: See bug for poc
Change-Id: I6bff1df385742b1d836d43180dc87fadcea80782
Git-repo: https://android.googlesource.com/kernel/msm
Git-commit: 0c702db4d90de88df11057bcf0d8fb2dfe741605
Signed-off-by: Dennis Cagle <d-cagle@codeaurora.org>
| -rw-r--r-- | drivers/staging/android/ion/ion.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c index b7fe42582e89..faa81c28a0d3 100644 --- a/drivers/staging/android/ion/ion.c +++ b/drivers/staging/android/ion/ion.c @@ -16,6 +16,7 @@ * */ +#include <linux/atomic.h> #include <linux/err.h> #include <linux/file.h> #include <linux/freezer.h> @@ -402,6 +403,15 @@ 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; +} + static int ion_handle_put_nolock(struct ion_handle *handle) { int ret; @@ -448,9 +458,9 @@ static 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); } struct ion_handle *ion_handle_get_by_id(struct ion_client *client, @@ -1412,7 +1422,7 @@ struct ion_handle *ion_import_dma_buf(struct ion_client *client, int fd) /* 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; } |