ASoC: soc-core: care NULL dirver name on snd_soc_lookup_component_nolocked()

[ Upstream commit 168873c ]

soc-generic-dmaengine-pcm.c uses same dev for both CPU and Platform.
In such case, CPU component driver might not have driver->name, then
snd_soc_lookup_component_nolocked() will be NULL pointer access error.
Care NULL driver name.

	Call trace:
	 strcmp from snd_soc_lookup_component_nolocked+0x64/0xa4
	 snd_soc_lookup_component_nolocked from snd_soc_unregister_component_by_driver+0x2c/0x44
	 snd_soc_unregister_component_by_driver from snd_dmaengine_pcm_unregister+0x28/0x64
	 snd_dmaengine_pcm_unregister from devres_release_all+0x98/0xfc
	 devres_release_all from device_unbind_cleanup+0xc/0x60
	 device_unbind_cleanup from really_probe+0x220/0x2c8
	 really_probe from __driver_probe_device+0x88/0x1a0
	 __driver_probe_device from driver_probe_device+0x30/0x110
	driver_probe_device from __driver_attach+0x90/0x178
	__driver_attach from bus_for_each_dev+0x7c/0xcc
	bus_for_each_dev from bus_add_driver+0xcc/0x1ec
	bus_add_driver from driver_register+0x80/0x11c
	driver_register from do_one_initcall+0x58/0x23c
	do_one_initcall from kernel_init_freeable+0x198/0x1f4
	kernel_init_freeable from kernel_init+0x1c/0x12c
	kernel_init from ret_from_fork+0x14/0x28

Fixes: 144d6df ("ASoC: soc-core: merge snd_soc_unregister_component() and snd_soc_unregister_component_by_driver()")
Reported-by: J. Neuschäfer <j.ne@posteo.net>
Closes: https://lore.kernel.org/r/aJb311bMDc9x-dpW@probook
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reported-by: Ondřej Jirman <megi@xff.cz>
Closes: https://lore.kernel.org/r/arxpwzu6nzgjxvsndct65ww2wz4aezb5gjdzlgr24gfx7xvyih@natjg6dg2pj6
Tested-by: J. Neuschäfer <j.ne@posteo.net>
Message-ID: <87ect8ysv8.wl-kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: morimoto

sound/soc/soc-core.c

@@ -375,8 +375,9 @@ struct snd_soc_component
 	for_each_component(component) {
 		if ((dev == component->dev) &&
 		    (!driver_name ||
-		     (driver_name == component->driver->name) ||
-		     (strcmp(component->driver->name, driver_name) == 0))) {
+		     (component->driver->name &&
+		      ((component->driver->name == driver_name) ||
+		       (strcmp(component->driver->name, driver_name) == 0))))) {
 			found_component = component;
 			break;
 		}