HID: hidraw: fix memory leak in hidraw_release()

Free the buffered reports before deleting the list entry.

BUG: memory leak
unreferenced object 0xffff88810e72f180 (size 32):
  comm "softirq", pid 0, jiffies 4294945143 (age 16.080s)
  hex dump (first 32 bytes):
    64 f3 c6 6a d1 88 07 04 00 00 00 00 00 00 00 00  d..j............
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff814ac6c3>] kmemdup+0x23/0x50 mm/util.c:128
    [<ffffffff8357c1d2>] kmemdup include/linux/fortify-string.h:440 [inline]
    [<ffffffff8357c1d2>] hidraw_report_event+0xa2/0x150 drivers/hid/hidraw.c:521
    [<ffffffff8356ddad>] hid_report_raw_event+0x27d/0x740 drivers/hid/hid-core.c:1992
    [<ffffffff8356e41e>] hid_input_report+0x1ae/0x270 drivers/hid/hid-core.c:2065
    [<ffffffff835f0d3f>] hid_irq_in+0x1ff/0x250 drivers/hid/usbhid/hid-core.c:284
    [<ffffffff82d3c7f9>] __usb_hcd_giveback_urb+0xf9/0x230 drivers/usb/core/hcd.c:1670
    [<ffffffff82d3cc26>] usb_hcd_giveback_urb+0x1b6/0x1d0 drivers/usb/core/hcd.c:1747
    [<ffffffff82ef1e14>] dummy_timer+0x8e4/0x14c0 drivers/usb/gadget/udc/dummy_hcd.c:1988
    [<ffffffff812f50a8>] call_timer_fn+0x38/0x200 kernel/time/timer.c:1474
    [<ffffffff812f5586>] expire_timers kernel/time/timer.c:1519 [inline]
    [<ffffffff812f5586>] __run_timers.part.0+0x316/0x430 kernel/time/timer.c:1790
    [<ffffffff812f56e4>] __run_timers kernel/time/timer.c:1768 [inline]
    [<ffffffff812f56e4>] run_timer_softirq+0x44/0x90 kernel/time/timer.c:1803
    [<ffffffff848000e6>] __do_softirq+0xe6/0x2ea kernel/softirq.c:571
    [<ffffffff81246db0>] invoke_softirq kernel/softirq.c:445 [inline]
    [<ffffffff81246db0>] __irq_exit_rcu kernel/softirq.c:650 [inline]
    [<ffffffff81246db0>] irq_exit_rcu+0xc0/0x110 kernel/softirq.c:662
    [<ffffffff84574f02>] sysvec_apic_timer_interrupt+0xa2/0xd0 arch/x86/kernel/apic/apic.c:1106
    [<ffffffff84600c8b>] asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:649
    [<ffffffff8458a070>] native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
    [<ffffffff8458a070>] arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
    [<ffffffff8458a070>] acpi_safe_halt drivers/acpi/processor_idle.c:111 [inline]
    [<ffffffff8458a070>] acpi_idle_do_entry+0xc0/0xd0 drivers/acpi/processor_idle.c:554

Link: https://syzkaller.appspot.com/bug?id=19a04b43c75ed1092021010419b5e560a8172c4f
Reported-by: syzbot+f59100a0428e6ded9443@syzkaller.appspotmail.com
Signed-off-by: Karthik Alapati <mail@karthek.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hidraw.c

@@ -350,6 +350,8 @@ static int hidraw_release(struct inode * inode, struct file * file)
 	down_write(&minors_rwsem);
 
 	spin_lock_irqsave(&hidraw_table[minor]->list_lock, flags);
+	for (int i = list->tail; i < list->head; i++)
+		kfree(list->buffer[i].value);
 	list_del(&list->node);
 	spin_unlock_irqrestore(&hidraw_table[minor]->list_lock, flags);
 	kfree(list);