linux-kernel - Re: [PATCH 5.10] xhci: check virt_dev is valid before dereferencing it

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Message-ID: <204adc683e0e71f227ba3f0c6126a80d9b281768.camel@omp.ru>
Date: Tue, 17 Sep 2024 10:38:06 +0000
From: Roman Smirnov <r.smirnov@....ru>
To: "stable@...r.kernel.org" <stable@...r.kernel.org>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC: Karina Yankevich <k.yankevich@....ru>, "rafael@...nel.org"
	<rafael@...nel.org>, "broonie@...nel.org" <broonie@...nel.org>, "Sergey
 Shtylyov" <s.shtylyov@....ru>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "lvc-project@...uxtesting.org"
	<lvc-project@...uxtesting.org>, Sergey Yudin <s.yudin@....ru>,
	"mathias.nyman@...ux.intel.com" <mathias.nyman@...ux.intel.com>
Subject: Re: [PATCH 5.10] xhci: check virt_dev is valid before dereferencing
 it

On Tue, 2024-09-17 at 13:07 +0300, Roman Smirnov wrote:
> From: Mathias Nyman <mathias.nyman@...ux.intel.com>
> 
> commit 03ed579d9d51aa018830b0de3e8b463faf6b87db upstream.
> 
> Check that the xhci_virt_dev structure that we dug out based
> on a slot_id value from a command completion is valid before
> dereferencing it.
> 
> Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
> Link: https://lore.kernel.org/r/20210129130044.206855-7-mathias.nyman@linux.intel.com
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Signed-off-by: Roman Smirnov <r.smirnov@....ru>
> ---
>  drivers/usb/host/xhci-ring.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> index fbb7a5b51ef4..a769803e7d38 100644
> --- a/drivers/usb/host/xhci-ring.c
> +++ b/drivers/usb/host/xhci-ring.c
> @@ -1415,6 +1415,8 @@ static void xhci_handle_cmd_config_ep(struct xhci_hcd *xhci, int slot_id,
>          * is not waiting on the configure endpoint command.
>          */
>         virt_dev = xhci->devs[slot_id];
> +       if (!virt_dev)
> +               return;
>         ctrl_ctx = xhci_get_input_control_ctx(virt_dev->in_ctx);
>         if (!ctrl_ctx) {
>                 xhci_warn(xhci, "Could not get input context, bad type.\n");
> @@ -1459,6 +1461,8 @@ static void xhci_handle_cmd_addr_dev(struct xhci_hcd *xhci, int slot_id)
>         struct xhci_slot_ctx *slot_ctx;
>  
>         vdev = xhci->devs[slot_id];
> +       if (!vdev)
> +               return;
>         slot_ctx = xhci_get_slot_ctx(xhci, vdev->out_ctx);
>         trace_xhci_handle_cmd_addr_dev(slot_ctx);
>  }
> @@ -1470,13 +1474,15 @@ static void xhci_handle_cmd_reset_dev(struct xhci_hcd *xhci, int slot_id,
>         struct xhci_slot_ctx *slot_ctx;
>  
>         vdev = xhci->devs[slot_id];
> +       if (!vdev) {
> +               xhci_warn(xhci, "Reset device command completion for disabled slot %u\n",
> +                         slot_id);
> +               return;
> +       }
>         slot_ctx = xhci_get_slot_ctx(xhci, vdev->out_ctx);
>         trace_xhci_handle_cmd_reset_dev(slot_ctx);
>  
>         xhci_dbg(xhci, "Completed reset device command.\n");
> -       if (!xhci->devs[slot_id])
> -               xhci_warn(xhci, "Reset device command completion "
> -                               "for disabled slot %u\n", slot_id);
>  }
>  
>  static void xhci_handle_cmd_nec_get_fw(struct xhci_hcd *xhci,

Sorry, I accidentally sent a copy to the wrong place. I've resent the patch.