media: Don't do DMA on stack for firmware upload in the AS102 driver

Firmware load on AS102 is using the stack which is not allowed any
longer. We currently fail with:

kernel: transfer buffer not dma capable
kernel: ------------[ cut here ]------------
kernel: WARNING: CPU: 0 PID: 598 at drivers/usb/core/hcd.c:1595 usb_hcd_map_urb_for_dma+0x41d/0x620
kernel: Modules linked in: amd64_edac_mod(-) edac_mce_amd as102_fe dvb_as102(+) kvm_amd kvm snd_hda_codec_realtek dvb_core snd_hda_codec_generic snd_hda_codec_hdmi snd_hda_intel snd_hda_codec irqbypass crct10dif_pclmul crc32_pclmul snd_hda_core snd_hwdep snd_seq ghash_clmulni_intel sp5100_tco fam15h_power wmi k10temp i2c_piix4 snd_seq_device snd_pcm snd_timer parport_pc parport tpm_infineon snd tpm_tis soundcore tpm_tis_core tpm shpchp acpi_cpufreq xfs libcrc32c amdgpu amdkfd amd_iommu_v2 radeon hid_logitech_hidpp i2c_algo_bit drm_kms_helper crc32c_intel ttm drm r8169 mii hid_logitech_dj
kernel: CPU: 0 PID: 598 Comm: systemd-udevd Not tainted 4.13.10-200.fc26.x86_64 #1
kernel: Hardware name: ASUS All Series/AM1I-A, BIOS 0505 03/13/2014
kernel: task: ffff979933b24c80 task.stack: ffffaf83413a4000
kernel: RIP: 0010:usb_hcd_map_urb_for_dma+0x41d/0x620
systemd-fsck[659]: /dev/sda2: clean, 49/128016 files, 268609/512000 blocks
kernel: RSP: 0018:ffffaf83413a7728 EFLAGS: 00010282
systemd-udevd[604]: link_config: autonegotiation is unset or enabled, the speed and duplex are not writable.
kernel: RAX: 000000000000001f RBX: ffff979930bce780 RCX: 0000000000000000
kernel: RDX: 0000000000000000 RSI: ffff97993ec0e118 RDI: ffff97993ec0e118
kernel: RBP: ffffaf83413a7768 R08: 000000000000039a R09: 0000000000000000
kernel: R10: 0000000000000001 R11: 00000000ffffffff R12: 00000000fffffff5
kernel: R13: 0000000001400000 R14: 0000000000000001 R15: ffff979930806800
kernel: FS: 00007effaca5c8c0(0000) GS:ffff97993ec00000(0000) knlGS:0000000000000000
kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
kernel: CR2: 00007effa9fca962 CR3: 0000000233089000 CR4: 00000000000406f0
kernel: Call Trace:
kernel: usb_hcd_submit_urb+0x493/0xb40
kernel: ? page_cache_tree_insert+0x100/0x100
kernel: ? xfs_iunlock+0xd5/0x100 [xfs]
kernel: ? xfs_file_buffered_aio_read+0x57/0xc0 [xfs]
kernel: usb_submit_urb+0x22d/0x560
kernel: usb_start_wait_urb+0x6e/0x180
kernel: usb_bulk_msg+0xb8/0x160
kernel: as102_send_ep1+0x49/0xe0 [dvb_as102]
kernel: ? devres_add+0x3f/0x50
kernel: as102_firmware_upload.isra.0+0x1dc/0x210 [dvb_as102]
kernel: as102_fw_upload+0xb6/0x1f0 [dvb_as102]
kernel: as102_dvb_register+0x2af/0x2d0 [dvb_as102]
kernel: as102_usb_probe+0x1f3/0x260 [dvb_as102]
kernel: usb_probe_interface+0x124/0x300
kernel: driver_probe_device+0x2ff/0x450
kernel: __driver_attach+0xa4/0xe0
kernel: ? driver_probe_device+0x450/0x450
kernel: bus_for_each_dev+0x6e/0xb0
kernel: driver_attach+0x1e/0x20
kernel: bus_add_driver+0x1c7/0x270
kernel: driver_register+0x60/0xe0
kernel: usb_register_driver+0x81/0x150
kernel: ? 0xffffffffc0807000
kernel: as102_usb_driver_init+0x1e/0x1000 [dvb_as102]
kernel: do_one_initcall+0x50/0x190
kernel: ? __vunmap+0x81/0xb0
kernel: ? kfree+0x154/0x170
kernel: ? kmem_cache_alloc_trace+0x15f/0x1c0
kernel: ? do_init_module+0x27/0x1e9
kernel: do_init_module+0x5f/0x1e9
kernel: load_module+0x2602/0x2c30
kernel: SYSC_init_module+0x170/0x1a0
kernel: ? SYSC_init_module+0x170/0x1a0
kernel: SyS_init_module+0xe/0x10
kernel: do_syscall_64+0x67/0x140
kernel: entry_SYSCALL64_slow_path+0x25/0x25
kernel: RIP: 0033:0x7effab6cf3ea
kernel: RSP: 002b:00007fff5cfcbbc8 EFLAGS: 00000246 ORIG_RAX: 00000000000000af
kernel: RAX: ffffffffffffffda RBX: 00005569e0b83760 RCX: 00007effab6cf3ea
kernel: RDX: 00007effac2099c5 RSI: 0000000000009a13 RDI: 00005569e0b98c50
kernel: RBP: 00007effac2099c5 R08: 00005569e0b83ed0 R09: 0000000000001d80
kernel: R10: 00007effab98db00 R11: 0000000000000246 R12: 00005569e0b98c50
kernel: R13: 00005569e0b81c60 R14: 0000000000020000 R15: 00005569dfadfdf7
kernel: Code: 48 39 c8 73 30 80 3d 59 60 9d 00 00 41 bc f5 ff ff ff 0f 85 26 ff ff ff 48 c7 c7 b8 6b d0 92 c6 05 3f 60 9d 00 01 e8 24 3d ad ff <0f> ff 8b 53 64 e9 09 ff ff ff 65 48 8b 0c 25 00 d3 00 00 48 8b
kernel: ---[ end trace c4cae366180e70ec ]---
kernel: as10x_usb: error during firmware upload part1

Let's allocate the the structure dynamically so we can get the firmware
loaded correctly:
[ 14.243057] as10x_usb: firmware: as102_data1_st.hex loaded with success
[ 14.500777] as10x_usb: firmware: as102_data2_st.hex loaded with success

Signed-off-by: Michele Baldessari <[e-mail]>
Cc: [e-mail]
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/usb/as102/as102_fw.c

···
 				 unsigned char *cmd,
 				 const struct firmware *firmware) {
 
-	struct as10x_fw_pkt_t fw_pkt;
+	struct as10x_fw_pkt_t *fw_pkt;
 	int total_read_bytes = 0, errno = 0;
 	unsigned char addr_has_changed = 0;
+
+	fw_pkt = kmalloc(sizeof(*fw_pkt), GFP_KERNEL);
+	if (!fw_pkt)
+		return -ENOMEM;
+
 
 	for (total_read_bytes = 0; total_read_bytes < firmware->size; ) {
 		int read_bytes = 0, data_len = 0;
···
 		/* parse intel hex line */
 		read_bytes = parse_hex_line(
 				(u8 *) (firmware->data + total_read_bytes),
-				fw_pkt.raw.address,
-				fw_pkt.raw.data,
+				fw_pkt->raw.address,
+				fw_pkt->raw.data,
 				&data_len,
 				&addr_has_changed);
 
···
 		/* detect the end of file */
 		total_read_bytes += read_bytes;
 		if (total_read_bytes == firmware->size) {
-			fw_pkt.u.request[0] = 0x00;
-			fw_pkt.u.request[1] = 0x03;
+			fw_pkt->u.request[0] = 0x00;
+			fw_pkt->u.request[1] = 0x03;
 
 			/* send EOF command */
 			errno = bus_adap->ops->upload_fw_pkt(bus_adap,
 							     (uint8_t *)
-							     &fw_pkt, 2, 0);
+							     fw_pkt, 2, 0);
 			if (errno < 0)
 				goto error;
 		} else {
 			if (!addr_has_changed) {
 				/* prepare command to send */
-				fw_pkt.u.request[0] = 0x00;
-				fw_pkt.u.request[1] = 0x01;
+				fw_pkt->u.request[0] = 0x00;
+				fw_pkt->u.request[1] = 0x01;
 
-				data_len += sizeof(fw_pkt.u.request);
-				data_len += sizeof(fw_pkt.raw.address);
+				data_len += sizeof(fw_pkt->u.request);
+				data_len += sizeof(fw_pkt->raw.address);
 
 				/* send cmd to device */
 				errno = bus_adap->ops->upload_fw_pkt(bus_adap,
 								     (uint8_t *)
-								     &fw_pkt,
+								     fw_pkt,
 								     data_len,
 								     0);
 				if (errno < 0)
···
 		}
 	}
 error:
+	kfree(fw_pkt);
 	return (errno == 0) ? total_read_bytes : errno;
 }