atlantic: Fix OOB read and write in hw_atl_utils_fw_rpc_wait

This bug report shows up when running our research tools. The
reports is SOOB read, but it seems SOOB write is also possible
a few lines below.

In details, fw.len and sw.len are inputs coming from io. A len
over the size of self->rpc triggers SOOB. The patch fixes the
bugs by adding sanity checks.

The bugs are triggerable with compromised/malfunctioning devices.
They are potentially exploitable given they first leak up to
0xffff bytes and able to overwrite the region later.

The patch is tested with QEMU emulater.
This is NOT tested with a real device.

Attached is the log we found by fuzzing.

BUG: KASAN: slab-out-of-bounds in
	hw_atl_utils_fw_upload_dwords+0x393/0x3c0 [atlantic]
Read of size 4 at addr ffff888016260b08 by task modprobe/213
CPU: 0 PID: 213 Comm: modprobe Not tainted 5.6.0 #1
Call Trace:
 dump_stack+0x76/0xa0
 print_address_description.constprop.0+0x16/0x200
 ? hw_atl_utils_fw_upload_dwords+0x393/0x3c0 [atlantic]
 ? hw_atl_utils_fw_upload_dwords+0x393/0x3c0 [atlantic]
 __kasan_report.cold+0x37/0x7c
 ? aq_hw_read_reg_bit+0x60/0x70 [atlantic]
 ? hw_atl_utils_fw_upload_dwords+0x393/0x3c0 [atlantic]
 kasan_report+0xe/0x20
 hw_atl_utils_fw_upload_dwords+0x393/0x3c0 [atlantic]
 hw_atl_utils_fw_rpc_call+0x95/0x130 [atlantic]
 hw_atl_utils_fw_rpc_wait+0x176/0x210 [atlantic]
 hw_atl_utils_mpi_create+0x229/0x2e0 [atlantic]
 ? hw_atl_utils_fw_rpc_wait+0x210/0x210 [atlantic]
 ? hw_atl_utils_initfw+0x9f/0x1c8 [atlantic]
 hw_atl_utils_initfw+0x12a/0x1c8 [atlantic]
 aq_nic_ndev_register+0x88/0x650 [atlantic]
 ? aq_nic_ndev_init+0x235/0x3c0 [atlantic]
 aq_pci_probe+0x731/0x9b0 [atlantic]
 ? aq_pci_func_init+0xc0/0xc0 [atlantic]
 local_pci_probe+0xd3/0x160
 pci_device_probe+0x23f/0x3e0
Reported-by: Brendan Dolan-Gavitt <brendandg@nyu.edu>
Signed-off-by: Zekun Shen <bruceshenzk@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/aquantia/atlantic/hw_atl/hw_atl_utils.c

@@ -559,6 +559,11 @@ int hw_atl_utils_fw_rpc_wait(struct aq_hw_s *self,
 			goto err_exit;
 
 		if (fw.len == 0xFFFFU) {
+			if (sw.len > sizeof(self->rpc)) {
+				printk(KERN_INFO "Invalid sw len: %x\n", sw.len);
+				err = -EINVAL;
+				goto err_exit;
+			}
 			err = hw_atl_utils_fw_rpc_call(self, sw.len);
 			if (err < 0)
 				goto err_exit;
@@ -567,6 +572,11 @@ int hw_atl_utils_fw_rpc_wait(struct aq_hw_s *self,
 
 	if (rpc) {
 		if (fw.len) {
+			if (fw.len > sizeof(self->rpc)) {
+				printk(KERN_INFO "Invalid fw len: %x\n", fw.len);
+				err = -EINVAL;
+				goto err_exit;
+			}
 			err =
 			hw_atl_utils_fw_downld_dwords(self,
 						      self->rpc_addr,