Some processors may mispredict an array bounds check and
speculatively access memory that they should not. With
a user supplied array index we like to play things safe
by masking the value with the array size before it is
used as an index.
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
---
V2: Mask the index *AFTER* the bounds check. Issue pointed
out by Gustavo. Fix suggested by Ira.
drivers/infiniband/core/user_mad.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c
index 9f8a48016b41..32cea5ed9ce1 100644
--- a/drivers/infiniband/core/user_mad.c
+++ b/drivers/infiniband/core/user_mad.c
@@ -49,6 +49,7 @@
#include <linux/sched.h>
#include <linux/semaphore.h>
#include <linux/slab.h>
+#include <linux/nospec.h>
#include <linux/uaccess.h>
@@ -888,7 +889,12 @@ static int ib_umad_unreg_agent(struct ib_umad_file *file, u32 __user *arg)
mutex_lock(&file->port->file_mutex);
mutex_lock(&file->mutex);
- if (id >= IB_UMAD_MAX_AGENTS || !__get_agent(file, id)) {
+ if (id >= IB_UMAD_MAX_AGENTS) {
+ ret = -EINVAL;
+ goto out;
+ }
+ id = array_index_nospec(id, IB_UMAD_MAX_AGENTS);
+ if (!__get_agent(file, id)) {
ret = -EINVAL;
goto out;
}
--
2.20.1
