[PATCH 4.19 02/18] dm: limit the number of targets and parameter size area

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mikulas Patocka <mpatocka@redhat.com>

commit bd504bcfec41a503b32054da5472904b404341a4 upstream.

The kvmalloc function fails with a warning if the size is larger than
INT_MAX. The warning was triggered by a syscall testing robot.

In order to avoid the warning, this commit limits the number of targets to
1048576 and the size of the parameter area to 1073741824.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
[srish: Apply to stable branch linux-4.19.y]
Signed-off-by: Srish Srinivasan <srish.srinivasan@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/md/dm-core.h  |    2 ++
 drivers/md/dm-ioctl.c |    3 ++-
 drivers/md/dm-table.c |    9 +++++++--
 3 files changed, 11 insertions(+), 3 deletions(-)

--- a/drivers/md/dm-core.h
+++ b/drivers/md/dm-core.h
@@ -18,6 +18,8 @@
 #include "dm.h"
 
 #define DM_RESERVED_MAX_IOS		1024
+#define DM_MAX_TARGETS			1048576
+#define DM_MAX_TARGET_PARAMS		1024
 
 struct dm_kobject_holder {
 	struct kobject kobj;
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1734,7 +1734,8 @@ static int copy_params(struct dm_ioctl _
 	if (copy_from_user(param_kernel, user, minimum_data_size))
 		return -EFAULT;
 
-	if (param_kernel->data_size < minimum_data_size)
+	if (unlikely(param_kernel->data_size < minimum_data_size) ||
+	    unlikely(param_kernel->data_size > DM_MAX_TARGETS * DM_MAX_TARGET_PARAMS))
 		return -EINVAL;
 
 	secure_data = param_kernel->flags & DM_SECURE_DATA_FLAG;
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -187,7 +187,12 @@ static int alloc_targets(struct dm_table
 int dm_table_create(struct dm_table **result, fmode_t mode,
 		    unsigned num_targets, struct mapped_device *md)
 {
-	struct dm_table *t = kzalloc(sizeof(*t), GFP_KERNEL);
+	struct dm_table *t;
+
+	if (num_targets > DM_MAX_TARGETS)
+		return -EOVERFLOW;
+
+	t = kzalloc(sizeof(*t), GFP_KERNEL);
 
 	if (!t)
 		return -ENOMEM;
@@ -202,7 +207,7 @@ int dm_table_create(struct dm_table **re
 
 	if (!num_targets) {
 		kfree(t);
-		return -ENOMEM;
+		return -EOVERFLOW;
 	}
 
 	if (alloc_targets(t, num_targets)) {