linux-kernel - Re: [PATCH] usb: gadget: f_fs: don't free buffer prematurely

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Date:   Wed, 20 Mar 2019 09:01:05 +0530
From:   mgautam@...eaurora.org
To:     fei.yang@...el.com
Cc:     balbi@...nel.org, gregkh@...uxfoundation.org,
        zhangjerry@...gle.com, andrzej.p@...labora.com,
        plr.vincent@...il.com, jingx.shen@...el.com,
        john.stultz@...aro.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-usb-owner@...r.kernel.org
Subject: Re: [PATCH] usb: gadget: f_fs: don't free buffer prematurely

On 2019-03-20 04:55, fei.yang@...el.com wrote:
> From: Fei Yang <fei.yang@...el.com>
> 
> The following kernel panic happens due to the io_data buffer gets 
> deallocated
> before the async io is completed. Add a check for the case where 
> io_data buffer
> should be deallocated by ffs_user_copy_worker.

[snip]

Please add tag - 'Fixes: 772a7a724f6 ("usb: gadget: f_fs: Allow 
scatter-gather buffers")


> ---
>  drivers/usb/gadget/function/f_fs.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/gadget/function/f_fs.c
> b/drivers/usb/gadget/function/f_fs.c
> index 20413c2..47be961 100644
> --- a/drivers/usb/gadget/function/f_fs.c
> +++ b/drivers/usb/gadget/function/f_fs.c
> @@ -1133,7 +1133,8 @@ static ssize_t ffs_epfile_io(struct file *file,
> struct ffs_io_data *io_data)
>  error_mutex:
>  	mutex_unlock(&epfile->mutex);
>  error:
> -	ffs_free_buffer(io_data);
> +	if (ret != -EIOCBQUEUED) /* don't free if there is iocb queued */
> +		ffs_free_buffer(io_data);
>  	return ret;
>  }