Re: [PATCH] usb: dwc3: Fix dentry leak in dwc3_gadget_free_endpoints

[Greg KH]

On Fri, Oct 28, 2022 at 04:49:19PM +0800, Cixi Geng wrote:
> From: Bruce Chen <bruce.chen@xxxxxxxxxx>
> 
> When using debugfs_remove_recursive leaks a dentry with
> a hotplug stress test, the phone runs out of memory.
> 
> Thus fix the issue by using the newly created debugfs_lookup_and_remove().
> 
> Signed-off-by: Bruce Chen <bruce.chen@xxxxxxxxxx>
> Signed-off-by: Cixi Geng <cixi.geng1@xxxxxxxxxx>
> ---
>  drivers/usb/dwc3/core.h    | 1 +
>  drivers/usb/dwc3/debugfs.c | 3 ++-
>  drivers/usb/dwc3/gadget.c  | 4 +---
>  3 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 8f9959ba9fd4..ba3ecaa7f06c 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -1261,6 +1261,7 @@ struct dwc3 {
>  	u8			num_eps;
>  
>  	struct dwc3_hwparams	hwparams;
> +	struct dentry		*root;

You forgot to document this new variable.

And name it a bit better?

>  	struct debugfs_regset32	*regset;
>  
>  	u32			dbg_lsp_select;
> diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
> index f2b7675c7f62..b9af4a81f51d 100644
> --- a/drivers/usb/dwc3/debugfs.c
> +++ b/drivers/usb/dwc3/debugfs.c
> @@ -911,6 +911,7 @@ void dwc3_debugfs_init(struct dwc3 *dwc)
>  	dwc->regset->base = dwc->regs - DWC3_GLOBALS_REGS_START;
>  
>  	root = debugfs_create_dir(dev_name(dwc->dev), usb_debug_root);
> +	dwc->root = root;
>  	debugfs_create_regset32("regdump", 0444, root, dwc->regset);
>  	debugfs_create_file("lsp_dump", 0644, root, dwc, &dwc3_lsp_fops);
>  
> @@ -929,6 +930,6 @@ void dwc3_debugfs_init(struct dwc3 *dwc)
>  
>  void dwc3_debugfs_exit(struct dwc3 *dwc)
>  {
> -	debugfs_remove(debugfs_lookup(dev_name(dwc->dev), usb_debug_root));
> +	debugfs_remove(dwc->root);
>  	kfree(dwc->regset);
>  }
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 079cd333632e..6d6c188fcbea 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -3172,9 +3172,7 @@ static void dwc3_gadget_free_endpoints(struct dwc3 *dwc)
>  			list_del(&dep->endpoint.ep_list);
>  		}
>  
> -		debugfs_remove_recursive(debugfs_lookup(dep->name,
> -				debugfs_lookup(dev_name(dep->dwc->dev),
> -					       usb_debug_root)));
> +		debugfs_lookup_and_remove(dep->name, dwc->root);
>  		kfree(dep);
>  	}
>  }
> -- 
> 2.34.1
> 

I don't think this is the full fix.

Below is a patch that I've had in a tree that I need to push out (along
with the other 33 debugfs_lookup patches) that should resolve this for
this driver in a more complete way.

Can you try this version instead?

thanks,

greg k-h

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