mmc: vub300: fix invalid response handling

commit a99d21c upstream.

We may get an empty response with zero length at the beginning of
the driver start and get following UBSAN error. Since there is no
content(SDRT_NONE) for the response, just return and skip the response
handling to avoid this problem.

Test pass : SDIO wifi throughput test with this patch

[  126.980684] UBSAN: array-index-out-of-bounds in drivers/mmc/host/vub300.c:1719:12
[  126.980709] index -1 is out of range for type 'u32 [4]'
[  126.980729] CPU: 4 PID: 9 Comm: kworker/u16:0 Tainted: G            E      6.3.0-rc4-mtk-local-202304272142 #1
[  126.980754] Hardware name: Intel(R) Client Systems NUC8i7BEH/NUC8BEB, BIOS BECFL357.86A.0081.2020.0504.1834 05/04/2020
[  126.980770] Workqueue: kvub300c vub300_cmndwork_thread [vub300]
[  126.980833] Call Trace:
[  126.980845]  <TASK>
[  126.980860]  dump_stack_lvl+0x48/0x70
[  126.980895]  dump_stack+0x10/0x20
[  126.980916]  ubsan_epilogue+0x9/0x40
[  126.980944]  __ubsan_handle_out_of_bounds+0x70/0x90
[  126.980979]  vub300_cmndwork_thread+0x58e7/0x5e10 [vub300]
[  126.981018]  ? _raw_spin_unlock+0x18/0x40
[  126.981042]  ? finish_task_switch+0x175/0x6f0
[  126.981070]  ? __switch_to+0x42e/0xda0
[  126.981089]  ? __switch_to_asm+0x3a/0x80
[  126.981129]  ? __pfx_vub300_cmndwork_thread+0x10/0x10 [vub300]
[  126.981174]  ? __kasan_check_read+0x11/0x20
[  126.981204]  process_one_work+0x7ee/0x13d0
[  126.981246]  worker_thread+0x53c/0x1240
[  126.981291]  kthread+0x2b8/0x370
[  126.981312]  ? __pfx_worker_thread+0x10/0x10
[  126.981336]  ? __pfx_kthread+0x10/0x10
[  126.981359]  ret_from_fork+0x29/0x50
[  126.981400]  </TASK>

Fixes: 88095e7 ("mmc: Add new VUB300 USB-to-SD/SDIO/MMC driver")
Signed-off-by: Deren Wu <deren.wu@mediatek.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/048cd6972c50c33c2e8f81d5228fed928519918b.1683987673.git.deren.wu@mediatek.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/mmc/host/vub300.c

@@ -1715,6 +1715,9 @@ static void construct_request_response(struct vub300_mmc_host *vub300,
 	int bytes = 3 & less_cmd;
 	int words = less_cmd >> 2;
 	u8 *r = vub300->resp.response.command_response;
+
+	if (!resp_len)
+		return;
 	if (bytes == 3) {
 		cmd->resp[words] = (r[1 + (words << 2)] << 24)
 			| (r[2 + (words << 2)] << 16)