[PATCH] vmci: prevent speculation leaks by sanitizing event in event_deliver()

Hagar Gamal Halim Hemdan
2023-11-27T19:48:33Z

Coverity spotted that event_msg is controlled by user-space,
event_msg->event_data.event is passed to event_deliver() and used
as an index without sanitization.

This change ensures that the event index is sanitized to mitigate any
possibility of speculative information leaks.

Fixes: 1d990201f9bb ("VMCI: event handling implementation.")

Signed-off-by: Hagar Gamal Halim Hemdan <hagarhem@amazon.com>
Cc: stable@vger.kernel.org
---
drivers/misc/vmw_vmci/vmci_event.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/vmw_vmci/vmci_event.c b/drivers/misc/vmw_vmci/vmci_event.c
index 5d7ac07623c2..9a41ab65378d 100644
--- a/drivers/misc/vmw_vmci/vmci_event.c
+++ b/drivers/misc/vmw_vmci/vmci_event.c
@@ -9,6 +9,7 @@
#include <linux/vmw_vmci_api.h>
#include <linux/list.h>
#include <linux/module.h>
+#include <linux/nospec.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/rculist.h>
@@ -86,9 +87,12 @@ static void event_deliver(struct vmci_event_msg *event_msg)
{
struct vmci_subscription *cur;
struct list_head *subscriber_list;
+ u32 sanitized_event, max_vmci_event;

rcu_read_lock();
- subscriber_list = &subscriber_array[event_msg->event_data.event];
+ max_vmci_event = ARRAY_SIZE(subscriber_array);
+ sanitized_event = array_index_nospec(event_msg->event_data.event, max_vmci_event);
+ subscriber_list = &subscriber_array[sanitized_event];
list_for_each_entry_rcu(cur, subscriber_list, node) {
cur->callback(cur->id, &event_msg->event_data,
cur->callback_data);
--
2.40.1