[PATCH 6.19 563/844] HID: logitech-hidpp: Check maxfield in hidpp_get_report_length()

[Sasha Levin]

From: Günther Noack <gnoack@xxxxxxxxxx>

[ Upstream commit 1547d41f9f19d691c2c9ce4c29f746297baef9e9 ]

Do not crash when a report has no fields.

Fake USB gadgets can send their own HID report descriptors and can define report
structures without valid fields.  This can be used to crash the kernel over USB.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Günther Noack <gnoack@xxxxxxxxxx>
Signed-off-by: Jiri Kosina <jkosina@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/hid/hid-logitech-hidpp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index ca96102121b85..02d83c3bd73d4 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -4314,7 +4314,7 @@ static int hidpp_get_report_length(struct hid_device *hdev, int id)
 
 	re = &(hdev->report_enum[HID_OUTPUT_REPORT]);
 	report = re->report_id_hash[id];
-	if (!report)
+	if (!report || !report->maxfield)
 		return 0;
 
 	return report->field[0]->report_count + 1;
-- 
2.51.0