diff options
| author | Daniel Rosenberg <drosen@google.com> | 2016-12-05 16:28:28 -0800 |
|---|---|---|
| committer | Mister Oyster <oysterized@gmail.com> | 2017-04-16 15:03:42 +0200 |
| commit | cff1a3c2d9b02ed8a1f1630191218b4905a05e65 (patch) | |
| tree | 36f347e03d577934e6ed9963001824a5429c5357 | |
| parent | f81ee65aedf25f7279cb1023081823e815a6e708 (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>
Signed-off-by: c_vkeert <vkeert@codeaurora.org>
| -rwxr-xr-x | drivers/staging/android/ion/ion.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c index a6a9b6ede..8b6da4807 100755 --- a/drivers/staging/android/ion/ion.c +++ b/drivers/staging/android/ion/ion.c @@ -15,6 +15,8 @@ */ #include <linux/device.h> +#include <linux/atomic.h> +#include <linux/err.h> #include <linux/file.h> #include <linux/freezer.h> #include <linux/fs.h> @@ -448,6 +450,15 @@ 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) { return kref_put(&handle->ref, ion_handle_destroy); @@ -490,9 +501,9 @@ 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, @@ -1394,7 +1405,7 @@ struct ion_handle *__ion_import_dma_buf(struct ion_client *client, int fd, int f /* 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; } |