diff options
| author | Daniel Rosenberg <drosen@google.com> | 2016-12-05 16:28:28 -0800 |
|---|---|---|
| committer | Ben Fennema <fennema@google.com> | 2017-09-28 12:07:21 -0700 |
| commit | 8e512b95ab3d54e97fc7b74aca4a6e1ce9037a6f (patch) | |
| tree | f0cf813c6dc38685cc2a7ab3dfa600deb165d99a | |
| parent | dcc60686fc68c0265ffc3fc5457c9d1167b18b63 (diff) | |
| download | mediatek-8e512b95ab3d54e97fc7b74aca4a6e1ce9037a6f.tar.gz | |
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
| -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 ae81e77afc6a..fa0d9390d30b 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> @@ -387,6 +388,15 @@ 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; @@ -433,9 +443,9 @@ 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, @@ -1211,7 +1221,7 @@ 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; } |