diff options
| author | Daniel Rosenberg <drosen@google.com> | 2018-08-30 16:09:46 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-09-05 09:20:11 +0200 |
| commit | 3af20bddda6f24b5a1c0072f2f6e3bb3ed04bf78 (patch) | |
| tree | 801d79540e6ca2c9746c6d4fc27881a91124e53b | |
| parent | b8c0e15469bab732065e64f7dffadab0b7103990 (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.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 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; } |