From: "Luck, Tony" tony.luck@intel.com
[ Upstream commit 61f259821dd3306e49b7d42a3f90fb5a4ff3351b ]
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@intel.com Link: https://lore.kernel.org/r/20190731043957.GA1600@agluck-desk2.amr.corp.intel.... Signed-off-by: Doug Ledford dledford@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/infiniband/core/user_mad.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c index 6511cb21f6e20..4a137bf584b04 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>
@@ -856,11 +857,14 @@ static int ib_umad_unreg_agent(struct ib_umad_file *file, u32 __user *arg)
if (get_user(id, arg)) return -EFAULT; + if (id >= IB_UMAD_MAX_AGENTS) + return -EINVAL;
mutex_lock(&file->port->file_mutex); mutex_lock(&file->mutex);
- if (id >= IB_UMAD_MAX_AGENTS || !__get_agent(file, id)) { + id = array_index_nospec(id, IB_UMAD_MAX_AGENTS); + if (!__get_agent(file, id)) { ret = -EINVAL; goto out; }