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Subject: Re: [PATCH] usb: xhci: Add error handling in xhci_map_urb_for_dma
To: Prashanth K <quic_prashk@quicinc.com>,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
 Mathias Nyman <mathias.nyman@intel.com>
Cc: linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
 stable@vger.kernel.org
References: <20240228083343.3101303-1-quic_prashk@quicinc.com>
From: Sergei Shtylyov <sergei.shtylyov@gmail.com>
Message-ID: <e4f87b6b-4561-8058-3449-2ff9086c81a4@gmail.com>
Date: Wed, 28 Feb 2024 12:01:06 +0300
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On 2/28/24 11:33 AM, Prashanth K wrote:

> Currently xhci_map_urb_for_dma() creates a temporary buffer
> and copies the SG list to the new linear buffer. But if the
> kzalloc_node() fails, then the following sg_pcopy_to_buffer()
> can lead to crash since it tries to memcpy to NULL pointer.
> So return -EAGAIN if kzalloc returns null pointer.
> 
> Cc: <stable@vger.kernel.org> # 5.11
> Fixes: 2017a1e58472 ("usb: xhci: Use temporary buffer to consolidate SG")
> Signed-off-by: Prashanth K <quic_prashk@quicinc.com>
> ---
>  drivers/usb/host/xhci.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index c057c42c36f4..0597a60bec34 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -1218,6 +1218,9 @@ static int xhci_map_temp_buffer(struct usb_hcd *hcd, struct urb *urb)
>  	temp = kzalloc_node(buf_len, GFP_ATOMIC,
>  			    dev_to_node(hcd->self.sysdev));
>  

   I don't think we need an empty line here.

> +	if (!temp)
> +		return -EAGAIN;

   Not -ENOMEM?

> +
>  	if (usb_urb_dir_out(urb))
>  		sg_pcopy_to_buffer(urb->sg, urb->num_sgs,
>  				   temp, buf_len, 0);

MBR, Sergey