[PATCH] ALSA: line6: fix uninit-value in line6_pod_process_message

[Edward Adam Davis <eadavis@qq.com>]

[Syzbot reported]
BUG: KMSAN: uninit-value in line6_pod_process_message+0x72f/0x7b0 sound/usb/line6/pod.c:201
 line6_pod_process_message+0x72f/0x7b0 sound/usb/line6/pod.c:201
 line6_data_received+0x5db/0x7e0 sound/usb/line6/driver.c:317
 __usb_hcd_giveback_urb+0x508/0x770 drivers/usb/core/hcd.c:1648
 usb_hcd_giveback_urb+0x157/0x720 drivers/usb/core/hcd.c:1732
 dummy_timer+0xd93/0x6b10 drivers/usb/gadget/udc/dummy_hcd.c:1987
 call_timer_fn+0x49/0x580 kernel/time/timer.c:1793
 expire_timers kernel/time/timer.c:1844 [inline]
 __run_timers kernel/time/timer.c:2418 [inline]
 __run_timer_base+0x84e/0xe90 kernel/time/timer.c:2429
 run_timer_base kernel/time/timer.c:2438 [inline]
 run_timer_softirq+0x3a/0x70 kernel/time/timer.c:2448
 __do_softirq+0x1c0/0x7d7 kernel/softirq.c:554
 invoke_softirq kernel/softirq.c:428 [inline]
 __irq_exit_rcu kernel/softirq.c:633 [inline]
 irq_exit_rcu+0x6a/0x130 kernel/softirq.c:645
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline]
 sysvec_apic_timer_interrupt+0x83/0x90 arch/x86/kernel/apic/apic.c:1043
 asm_sysvec_apic_timer_interrupt+0x1f/0x30 arch/x86/include/asm/idtentry.h:702
 native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
 arch_safe_halt arch/x86/include/asm/irqflags.h:86 [inline]
 acpi_safe_halt+0x25/0x30 drivers/acpi/processor_idle.c:112
 acpi_idle_do_entry+0x22/0x40 drivers/acpi/processor_idle.c:573
 acpi_idle_enter+0xa1/0xc0 drivers/acpi/processor_idle.c:707
 cpuidle_enter_state+0xcb/0x250 drivers/cpuidle/cpuidle.c:267
 cpuidle_enter+0x7f/0xf0 drivers/cpuidle/cpuidle.c:388
 call_cpuidle kernel/sched/idle.c:155 [inline]
 cpuidle_idle_call kernel/sched/idle.c:236 [inline]
 do_idle+0x551/0x750 kernel/sched/idle.c:332
 cpu_startup_entry+0x65/0x80 kernel/sched/idle.c:430
 rest_init+0x1e8/0x260 init/main.c:732
 start_kernel+0x927/0xa70 init/main.c:1074
 x86_64_start_reservations+0x2e/0x30 arch/x86/kernel/head64.c:507
 x86_64_start_kernel+0x98/0xa0 arch/x86/kernel/head64.c:488
 common_startup_64+0x12c/0x137

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:3804 [inline]
 slab_alloc_node mm/slub.c:3845 [inline]
 kmalloc_trace+0x578/0xba0 mm/slub.c:3992
 kmalloc include/linux/slab.h:628 [inline]
 line6_init_cap_control+0x4f1/0x770 sound/usb/line6/driver.c:700
 line6_probe+0xeae/0x1120 sound/usb/line6/driver.c:797
 pod_probe+0x79/0x90 sound/usb/line6/pod.c:522
 usb_probe_interface+0xd6f/0x1350 drivers/usb/core/driver.c:399
 really_probe+0x4db/0xd90 drivers/base/dd.c:656
 __driver_probe_device+0x2ab/0x5d0 drivers/base/dd.c:798
 driver_probe_device+0x72/0x890 drivers/base/dd.c:828
 __device_attach_driver+0x568/0x9e0 drivers/base/dd.c:956
 bus_for_each_drv+0x403/0x620 drivers/base/bus.c:457
 __device_attach+0x3c1/0x650 drivers/base/dd.c:1028
 device_initial_probe+0x32/0x40 drivers/base/dd.c:1077
 bus_probe_device+0x3dc/0x5c0 drivers/base/bus.c:532
 device_add+0x1475/0x1c90 drivers/base/core.c:3705
 usb_set_configuration+0x31c9/0x38d0 drivers/usb/core/message.c:2210
 usb_generic_driver_probe+0x109/0x2a0 drivers/usb/core/generic.c:254
 usb_probe_device+0x3a7/0x690 drivers/usb/core/driver.c:294
 really_probe+0x4db/0xd90 drivers/base/dd.c:656
 __driver_probe_device+0x2ab/0x5d0 drivers/base/dd.c:798
 driver_probe_device+0x72/0x890 drivers/base/dd.c:828
 __device_attach_driver+0x568/0x9e0 drivers/base/dd.c:956
 bus_for_each_drv+0x403/0x620 drivers/base/bus.c:457
 __device_attach+0x3c1/0x650 drivers/base/dd.c:1028
 device_initial_probe+0x32/0x40 drivers/base/dd.c:1077
 bus_probe_device+0x3dc/0x5c0 drivers/base/bus.c:532
 device_add+0x1475/0x1c90 drivers/base/core.c:3705
 usb_new_device+0x15ff/0x2470 drivers/usb/core/hub.c:2643
 hub_port_connect drivers/usb/core/hub.c:5512 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5652 [inline]
 port_event drivers/usb/core/hub.c:5812 [inline]
 hub_event+0x4ff8/0x72d0 drivers/usb/core/hub.c:5894
 process_one_work kernel/workqueue.c:3254 [inline]
 process_scheduled_works+0xa81/0x1bd0 kernel/workqueue.c:3335
 worker_thread+0xea5/0x1560 kernel/workqueue.c:3416
 kthread+0x3e2/0x540 kernel/kthread.c:388
 ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
[Fix]
Let's clear all the content of the buffer message during alloc.

Reported-and-tested-by: syzbot+7fb05ccf7b3d2f9617b3@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 sound/usb/line6/driver.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/usb/line6/driver.c b/sound/usb/line6/driver.c
index b67617b68e50..8fd9d42aa8e2 100644
--- a/sound/usb/line6/driver.c
+++ b/sound/usb/line6/driver.c
@@ -697,7 +697,7 @@ static int line6_init_cap_control(struct usb_line6 *line6)
 		return -ENOMEM;
 
 	if (line6->properties->capabilities & LINE6_CAP_CONTROL_MIDI) {
-		line6->buffer_message = kmalloc(LINE6_MIDI_MESSAGE_MAXLEN, GFP_KERNEL);
+		line6->buffer_message = kzalloc(LINE6_MIDI_MESSAGE_MAXLEN, GFP_KERNEL);
 		if (!line6->buffer_message)
 			return -ENOMEM;
 
-- 
2.43.0