[PATCH 5.15.y 1/4] s390/vfio_ccw: Ensure index for read/write regions are within range

[Sasha Levin <sashal@kernel.org>]

From: Eric Farman <farman@linux.ibm.com>

[ Upstream commit 9f5f9a78fedc45bc29d6a0a64e3a3472361afae5 ]

The introduction of the capability chain rightly clamped the
region indexes to the range of the capabilities itself, but
neglected to do so for the existing read/write regions which
should also be enforced.

Fixes: db8e5d17ac03 ("vfio-ccw: add capabilities chain")
Cc: stable@vger.kernel.org
Cc: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Stable-dep-of: 16b0798024c0 ("s390/vfio_ccw: Implement a crw lock")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/s390/cio/vfio_ccw_async.c | 16 ++++++++++++++++
 drivers/s390/cio/vfio_ccw_chp.c   | 15 +++++++++++++++
 drivers/s390/cio/vfio_ccw_ops.c   |  7 +++----
 3 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_async.c b/drivers/s390/cio/vfio_ccw_async.c
index 7a838e3d7c0fa..01f8cedc46e2a 100644
--- a/drivers/s390/cio/vfio_ccw_async.c
+++ b/drivers/s390/cio/vfio_ccw_async.c
@@ -8,6 +8,7 @@
  */
 
 #include <linux/vfio.h>
+#include <linux/nospec.h>
 #include <linux/mdev.h>
 
 #include "vfio_ccw_private.h"
@@ -25,11 +26,20 @@ static ssize_t vfio_ccw_async_region_read(struct vfio_ccw_private *private,
 		return -EINVAL;
 
 	mutex_lock(&private->io_mutex);
+
+	if (i >= private->num_regions) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	i = array_index_nospec(i, private->num_regions);
 	region = private->region[i].data;
 	if (copy_to_user(buf, (void *)region + pos, count))
 		ret = -EFAULT;
 	else
 		ret = count;
+
+out_unlock:
 	mutex_unlock(&private->io_mutex);
 	return ret;
 }
@@ -49,6 +59,12 @@ static ssize_t vfio_ccw_async_region_write(struct vfio_ccw_private *private,
 	if (!mutex_trylock(&private->io_mutex))
 		return -EAGAIN;
 
+	if (i >= private->num_regions) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	i = array_index_nospec(i, private->num_regions);
 	region = private->region[i].data;
 	if (copy_from_user((void *)region + pos, buf, count)) {
 		ret = -EFAULT;
diff --git a/drivers/s390/cio/vfio_ccw_chp.c b/drivers/s390/cio/vfio_ccw_chp.c
index 13b26a1c79886..11264e2adffcb 100644
--- a/drivers/s390/cio/vfio_ccw_chp.c
+++ b/drivers/s390/cio/vfio_ccw_chp.c
@@ -9,6 +9,7 @@
  */
 
 #include <linux/slab.h>
+#include <linux/nospec.h>
 #include <linux/vfio.h>
 #include "vfio_ccw_private.h"
 
@@ -25,6 +26,13 @@ static ssize_t vfio_ccw_schib_region_read(struct vfio_ccw_private *private,
 		return -EINVAL;
 
 	mutex_lock(&private->io_mutex);
+
+	if (i >= private->num_regions) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	i = array_index_nospec(i, private->num_regions);
 	region = private->region[i].data;
 
 	if (cio_update_schib(private->sch)) {
@@ -96,6 +104,12 @@ static ssize_t vfio_ccw_crw_region_read(struct vfio_ccw_private *private,
 		list_del(&crw->next);
 
 	mutex_lock(&private->io_mutex);
+	if (i >= private->num_regions) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	i = array_index_nospec(i, private->num_regions);
 	region = private->region[i].data;
 
 	if (crw)
@@ -108,6 +122,7 @@ static ssize_t vfio_ccw_crw_region_read(struct vfio_ccw_private *private,
 
 	region->crw = 0;
 
+out:
 	mutex_unlock(&private->io_mutex);
 
 	kfree(crw);
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 7f540ad0b568b..b76b0521b456b 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -251,6 +251,7 @@ static ssize_t vfio_ccw_mdev_read(struct mdev_device *mdev,
 		return vfio_ccw_mdev_read_io_region(private, buf, count, ppos);
 	default:
 		index -= VFIO_CCW_NUM_REGIONS;
+		index = array_index_nospec(index, private->num_regions);
 		return private->region[index].ops->read(private, buf, count,
 							ppos);
 	}
@@ -304,6 +305,7 @@ static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev,
 		return vfio_ccw_mdev_write_io_region(private, buf, count, ppos);
 	default:
 		index -= VFIO_CCW_NUM_REGIONS;
+		index = array_index_nospec(index, private->num_regions);
 		return private->region[index].ops->write(private, buf, count,
 							 ppos);
 	}
@@ -351,11 +353,8 @@ static int vfio_ccw_mdev_get_region_info(struct vfio_region_info *info,
 		    VFIO_CCW_NUM_REGIONS + private->num_regions)
 			return -EINVAL;
 
-		info->index = array_index_nospec(info->index,
-						 VFIO_CCW_NUM_REGIONS +
-						 private->num_regions);
-
 		i = info->index - VFIO_CCW_NUM_REGIONS;
+		i = array_index_nospec(i, private->num_regions);
 
 		info->offset = VFIO_CCW_INDEX_TO_OFFSET(info->index);
 		info->size = private->region[i].size;
-- 
2.53.0