[dm-devel] [PATCH] dm-ioctl: log an error if the ioctl structure is corrupted

[Mikulas Patocka]

Log an error if the ioctl structure is corrupted. This will help us triage
bugs when when userspace is passing invalid ioctl structure to the kernel.

Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>

---
 drivers/md/dm-ioctl.c |   14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

Index: linux-dm/drivers/md/dm-ioctl.c
===================================================================
--- linux-dm.orig/drivers/md/dm-ioctl.c	2022-03-17 19:19:31.000000000 +0100
+++ linux-dm/drivers/md/dm-ioctl.c	2022-03-20 20:37:34.000000000 +0100
@@ -891,15 +891,21 @@ static struct hash_cell *__find_device_h
 	struct hash_cell *hc = NULL;
 
 	if (*param->uuid) {
-		if (*param->name || param->dev)
+		if (*param->name || param->dev) {
+			DMWARN("Invalid ioctl structure: uuid %s, name %s, dev %llx",
+				param->uuid, param->name, (unsigned long long)param->dev);
 			return NULL;
+		}
 
 		hc = __get_uuid_cell(param->uuid);
 		if (!hc)
 			return NULL;
 	} else if (*param->name) {
-		if (param->dev)
+		if (param->dev) {
+			DMWARN("Invalid ioctl structure: name %s, dev %llx",
+				param->name, (unsigned long long)param->dev);
 			return NULL;
+		}
 
 		hc = __get_name_cell(param->name);
 		if (!hc)
@@ -1851,8 +1857,10 @@ 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 (param_kernel->data_size < minimum_data_size) {
+		DMWARN("Invalid data size in the ioctl structure: %u", param_kernel->data_size);
 		return -EINVAL;
+	}
 
 	secure_data = param_kernel->flags & DM_SECURE_DATA_FLAG;