[PATCH v2] usb: dwc3: core: Prevent USB core invalid event buffer address access

[Selvarasu Ganesan <selvarasu.g@samsung.com>]

This commit addresses an issue where the USB core could access an
invalid event buffer address during runtime suspend, potentially causing
SMMU faults and other memory issues. The problem arises from the
following sequence.
        1. In dwc3_gadget_suspend, there is a chance of a timeout when
        moving the USB core to the halt state after clearing the
        run/stop bit by software.
        2. In dwc3_core_exit, the event buffer is cleared regardless of
        the USB core's status, which may lead to an SMMU faults and
        other memory issues. if the USB core tries to access the event
        buffer address.

To prevent this issue, this commit ensures that the event buffer address
is not cleared by software  when the USB core is active during runtime
suspend by checking its status before clearing the buffer address.

Cc: stable@vger.kernel.org
Fixes: 89d7f9629946 ("usb: dwc3: core: Skip setting event buffers for host only controllers")
Signed-off-by: Selvarasu Ganesan <selvarasu.g@samsung.com>
---

Changes in v2:
- Added separate check for USB controller status before cleaning the
  event buffer.
- Link to v1: https://lore.kernel.org/lkml/20240722145617.537-1-selvarasu.g@samsung.com/
---
 drivers/usb/dwc3/core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 734de2a8bd21..5b67d9bca71b 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -564,10 +564,15 @@ int dwc3_event_buffers_setup(struct dwc3 *dwc)
 void dwc3_event_buffers_cleanup(struct dwc3 *dwc)
 {
 	struct dwc3_event_buffer	*evt;
+	u32				reg;
 
 	if (!dwc->ev_buf)
 		return;
 
+	reg = dwc3_readl(dwc->regs, DWC3_DSTS);
+	if (!(reg & DWC3_DSTS_DEVCTRLHLT))
+		return;
+
 	evt = dwc->ev_buf;
 
 	evt->lpos = 0;
-- 
2.17.1