diff --git a/fs/ksmbd/smb2ops.c b/fs/ksmbd/smb2ops.c
index b06456eb587b..fb6a65d23139 100644
--- a/fs/ksmbd/smb2ops.c
+++ b/fs/ksmbd/smb2ops.c
@@ -284,6 +284,7 @@ int init_smb3_11_server(struct ksmbd_conn *conn)
 
 void init_smb2_max_read_size(unsigned int sz)
 {
+	sz = clamp_val(sz, SMB3_MIN_IOSIZE, SMB3_MAX_IOSIZE);
 	smb21_server_values.max_read_size = sz;
 	smb30_server_values.max_read_size = sz;
 	smb302_server_values.max_read_size = sz;
@@ -292,6 +293,7 @@ void init_smb2_max_read_size(unsigned int sz)
 
 void init_smb2_max_write_size(unsigned int sz)
 {
+	sz = clamp_val(sz, SMB3_MIN_IOSIZE, SMB3_MAX_IOSIZE);
 	smb21_server_values.max_write_size = sz;
 	smb30_server_values.max_write_size = sz;
 	smb302_server_values.max_write_size = sz;
@@ -300,6 +302,7 @@ void init_smb2_max_write_size(unsigned int sz)
 
 void init_smb2_max_trans_size(unsigned int sz)
 {
+	sz = clamp_val(sz, SMB3_MIN_IOSIZE, SMB3_MAX_IOSIZE);
 	smb21_server_values.max_trans_size = sz;
 	smb30_server_values.max_trans_size = sz;
 	smb302_server_values.max_trans_size = sz;
diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 89c187aa8db2..7999d8bc6892 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -524,7 +524,7 @@ int smb2_allocate_rsp_buf(struct ksmbd_work *work)
 {
 	struct smb2_hdr *hdr = work->request_buf;
 	size_t small_sz = MAX_CIFS_SMALL_BUFFER_SIZE;
-	size_t large_sz = work->conn->vals->max_trans_size + MAX_SMB2_HDR_SIZE;
+	size_t large_sz = small_sz + work->conn->vals->max_trans_size;
 	size_t sz = small_sz;
 	int cmd = le16_to_cpu(hdr->Command);
 
diff --git a/fs/ksmbd/smb2pdu.h b/fs/ksmbd/smb2pdu.h
index a6dec5ec6a54..ff5a2f01d34a 100644
--- a/fs/ksmbd/smb2pdu.h
+++ b/fs/ksmbd/smb2pdu.h
@@ -113,6 +113,8 @@
 #define SMB21_DEFAULT_IOSIZE	(1024 * 1024)
 #define SMB3_DEFAULT_IOSIZE	(4 * 1024 * 1024)
 #define SMB3_DEFAULT_TRANS_SIZE	(1024 * 1024)
+#define SMB3_MIN_IOSIZE	(64 * 1024)
+#define SMB3_MAX_IOSIZE	(8 * 1024 * 1024)
 
 /*
  * SMB2 Header Definition