usb: dwc3: gadget: check that event count does not exceed event buffer length

The event count is read from register DWC3_GEVNTCOUNT.
There is a check for the count being zero, but not for exceeding the
event buffer length.
Check that event count does not exceed event buffer length,
avoiding an out-of-bounds access when memcpy'ing the event.
Crash log:
Unable to handle kernel paging request at virtual address ffffffc0129be000
pc : __memcpy+0x114/0x180
lr : dwc3_check_event_buf+0xec/0x348
x3 : 0000000000000030 x2 : 000000000000dfc4
x1 : ffffffc0129be000 x0 : ffffff87aad60080
Call trace:
__memcpy+0x114/0x180
dwc3_interrupt+0x24/0x34

Signed-off-by: Frode Isaksen <frode@meta.com>
Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver")
Cc: stable <stable@kernel.org>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/20250403072907.448524-1-fisaksen@baylibre.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 47e73c4ed62d3ec52f0e8f5c3d5ef1aae4065771..8c30d86cc4e3a00ef624621f13063e2c37330029 100644 (file)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -4617,6 +4617,12 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt)
        if (!count)
                return IRQ_NONE;
 
+       if (count > evt->length) {
+               dev_err_ratelimited(dwc->dev, "invalid count(%u) > evt->length(%u)\n",
+                       count, evt->length);
+               return IRQ_NONE;
+       }
+
        evt->count = count;
        evt->flags |= DWC3_EVENT_PENDING;