[SRU][F/J][PATCH 2/2] dm: limit the number of targets and parameter size area

[Yuxuan Luo]

From: Mikulas Patocka <mpatocka at redhat.com>

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 at redhat.com>
Signed-off-by: Mike Snitzer <snitzer at kernel.org>
(cherry picked from commit bd504bcfec41a503b32054da5472904b404341a4)
CVE-2024-23851
Signed-off-by: Yuxuan Luo <yuxuan.luo at canonical.com>
---
 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(-)

diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h
index 5a7d270b32c01..eff11df6c32e5 100644
--- a/drivers/md/dm-core.h
+++ b/drivers/md/dm-core.h
@@ -21,6 +21,8 @@
 #include "dm-ima.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;
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index ec72963b10045..577b6e9199476 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1865,7 +1865,8 @@ static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kern
 	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)) {
 		DMERR("Invalid data size in the ioctl structure: %u",
 		      param_kernel->data_size);
 		return -EINVAL;
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 46ec4590f62f6..52083d397fc4b 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -126,7 +126,12 @@ static int alloc_targets(struct dm_table *t, unsigned int num)
 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;
@@ -140,7 +145,7 @@ int dm_table_create(struct dm_table **result, fmode_t mode,
 
 	if (!num_targets) {
 		kfree(t);
-		return -ENOMEM;
+		return -EOVERFLOW;
 	}
 
 	if (alloc_targets(t, num_targets)) {
-- 
2.34.1