From: Daniel Rosenberg <drosen@google.com>
To: stable@vger.kernel.org, Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org, kernel-team@android.com,
Daniel Rosenberg <drosen@google.com>
Subject: [PATCH] staging: android: ion: check for kref overflow
Date: Thu, 30 Aug 2018 16:09:46 -0700 [thread overview]
Message-ID: <20180830230946.228701-1-drosen@google.com> (raw)
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>
---
drivers/staging/android/ion/ion.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index 6f9974cb0e152..48821948fa487 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);
}
struct ion_handle *ion_handle_get_by_id(struct ion_client *client,
@@ -1100,7 +1111,7 @@ 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;
}
--
2.19.0.rc0.228.g281dcd1b4d0-goog
next reply other threads:[~2018-08-30 23:10 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-30 23:09 Daniel Rosenberg [this message]
2018-08-31 0:41 ` [PATCH] staging: android: ion: check for kref overflow Greg Kroah-Hartman
2018-08-31 1:36 ` Daniel Rosenberg
2018-08-31 15:56 ` Greg Kroah-Hartman
2018-08-31 21:31 ` Daniel Rosenberg
2018-09-03 16:31 ` Greg Kroah-Hartman
-- strict thread matches above, loose matches on Subject: below --
2018-08-21 1:30 Daniel Rosenberg
2018-08-21 5:13 ` Greg Kroah-Hartman
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