linux-kernel - Re: [PATCH v2] usb: dwc3: core: Prevent USB core invalid event buffer address access

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Message-ID: <9de9be29-2f75-41a1-931b-f8cf0a9904ac@quicinc.com>
Date: Mon, 19 Aug 2024 14:58:46 +0530
From: Krishna Kurapati <quic_kriskura@...cinc.com>
To: Selvarasu Ganesan <selvarasu.g@...sung.com>, <Thinh.Nguyen@...opsys.com>,
        <gregkh@...uxfoundation.org>
CC: <jh0801.jung@...sung.com>, <dh10.jung@...sung.com>, <naushad@...sung.com>,
        <akash.m5@...sung.com>, <rc93.raju@...sung.com>,
        <linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <taehyun.cho@...sung.com>, <hongpooh.kim@...sung.com>,
        <eomji.oh@...sung.com>, <shijie.cai@...sung.com>,
        <stable@...r.kernel.org>
Subject: Re: [PATCH v2] usb: dwc3: core: Prevent USB core invalid event buffer
 address access



On 8/8/2024 5:35 PM, Selvarasu Ganesan wrote:
> 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@...r.kernel.org
> Fixes: 89d7f9629946 ("usb: dwc3: core: Skip setting event buffers for host only controllers")

I don't think the fixes tag is right.

This fix is independent of whether controller is host only capable or 
not. This is fixing the original commit that introduced the cleanup call.

Regards,
Krishna,

> Signed-off-by: Selvarasu Ganesan <selvarasu.g@...sung.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;