usb: raw-gadget: fix memory leak in gadget_setup

When fetch 'event' from event queue, after copy its address
space content to user space, the 'event' the memory space
pointed to by the 'event' pointer need be freed.

BUG: memory leak
unreferenced object 0xffff888110622660 (size 32):
  comm "softirq", pid 0, jiffies 4294941981 (age 12.480s)
  hex dump (first 32 bytes):
    02 00 00 00 08 00 00 00 80 06 00 01 00 00 40 00  ..............@.
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000efd29abd>] kmalloc include/linux/slab.h:554 [inline]
    [<00000000efd29abd>] raw_event_queue_add drivers/usb/gadget/legacy/raw_gadget.c:66 [inline]
    [<00000000efd29abd>] raw_queue_event drivers/usb/gadget/legacy/raw_gadget.c:225 [inline]
    [<00000000efd29abd>] gadget_setup+0xf6/0x220 drivers/usb/gadget/legacy/raw_gadget.c:343
    [<00000000952c4a46>] dummy_timer+0xb9f/0x14c0 drivers/usb/gadget/udc/dummy_hcd.c:1899
    [<0000000074ac2c54>] call_timer_fn+0x38/0x200 kernel/time/timer.c:1415
    [<00000000560a3a79>] expire_timers kernel/time/timer.c:1460 [inline]
    [<00000000560a3a79>] __run_timers.part.0+0x319/0x400 kernel/time/timer.c:1757
    [<000000009d9503d0>] __run_timers kernel/time/timer.c:1738 [inline]
    [<000000009d9503d0>] run_timer_softirq+0x3d/0x80 kernel/time/timer.c:1770
    [<000000009df27c89>] __do_softirq+0xcc/0x2c2 kernel/softirq.c:298
    [<000000007a3f1a47>] asm_call_irq_on_stack+0xf/0x20
    [<000000004a62cc2e>] __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
    [<000000004a62cc2e>] run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
    [<000000004a62cc2e>] do_softirq_own_stack+0x32/0x40 arch/x86/kernel/irq_64.c:77
    [<00000000b0086800>] invoke_softirq kernel/softirq.c:393 [inline]
    [<00000000b0086800>] __irq_exit_rcu kernel/softirq.c:423 [inline]
    [<00000000b0086800>] irq_exit_rcu+0x91/0xc0 kernel/softirq.c:435
    [<00000000175f9523>] sysvec_apic_timer_interrupt+0x36/0x80 arch/x86/kernel/apic/apic.c:1091
    [<00000000a348e847>] asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:631
    [<0000000060661100>] native_safe_halt arch/x86/include/asm/irqflags.h:60 [inline]
    [<0000000060661100>] arch_safe_halt arch/x86/include/asm/irqflags.h:103 [inline]
    [<0000000060661100>] acpi_safe_halt drivers/acpi/processor_idle.c:111 [inline]
    [<0000000060661100>] acpi_idle_do_entry+0xc3/0xd0 drivers/acpi/processor_idle.c:517
    [<000000003f413b99>] acpi_idle_enter+0x128/0x1f0 drivers/acpi/processor_idle.c:648
    [<00000000f5e5afb8>] cpuidle_enter_state+0xc9/0x650 drivers/cpuidle/cpuidle.c:237
    [<00000000d50d51fc>] cpuidle_enter+0x29/0x40 drivers/cpuidle/cpuidle.c:351
    [<00000000d674baed>] call_cpuidle kernel/sched/idle.c:132 [inline]
    [<00000000d674baed>] cpuidle_idle_call kernel/sched/idle.c:213 [inline]
    [<00000000d674baed>] do_idle+0x1c8/0x250 kernel/sched/idle.c:273

Reported-by: syzbot+bd38200f53df6259e6bf@syzkaller.appspotmail.com
Signed-off-by: Zqiang <qiang.zhang@windriver.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

drivers/usb/gadget/legacy/raw_gadget.c

@@ -564,9 +564,12 @@ static int raw_ioctl_event_fetch(struct raw_dev *dev, unsigned long value)
 		return -ENODEV;
 	}
 	length = min(arg.length, event->length);
-	if (copy_to_user((void __user *)value, event, sizeof(*event) + length))
+	if (copy_to_user((void __user *)value, event, sizeof(*event) + length)) {
+		kfree(event);
 		return -EFAULT;
+	}
 
+	kfree(event);
 	return 0;
 }