linux-kernel - Re: [PATCH] misc: fastrpc: Fix double free of 'buf' in error path

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Message-ID: <b0115d7d-d15a-4948-8726-09a8b37f3f36@kili.mountain>
Date:   Fri, 19 May 2023 13:22:19 +0300
From:   Dan Carpenter <dan.carpenter@...aro.org>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc:     Sukrut Bellary <sukrut.bellary@...ux.com>,
        Abel Vesa <abel.vesa@...aro.org>,
        Amol Maheshwari <amahesh@....qualcomm.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH] misc: fastrpc: Fix double free of 'buf' in error path

> ----------------------->cut<---------------------------
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index f60bbf99485c..3fdd326e1ae8 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -1891,7 +1891,8 @@ static int fastrpc_req_mmap(struct fastrpc_user *fl,
> char __user *argp)
>                                       &args[0]);
>         if (err) {
>                 dev_err(dev, "mmap error (len 0x%08llx)\n", buf->size);
> -               goto err_invoke;
> +               fastrpc_buf_free(buf);
> +               return err;
>         }
> 
>         /* update the buffer to be able to deallocate the memory on the DSP
> */
> @@ -1930,11 +1931,7 @@ static int fastrpc_req_mmap(struct fastrpc_user *fl,
> char __user *argp)
>         return 0;
> 
>  err_assign:
> -       fastrpc_req_munmap_impl(fl, buf);
> -err_invoke:
> -       fastrpc_buf_free(buf);
> -
> -       return err;
> +       return fastrpc_req_munmap_impl(fl, buf);

This will return success if copy_to_user() fails.

regards,
dan carpenter