linux-kernel - Re: [PATCH] usb: mon: make mmapped memory read only

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Message-ID: <20220919042533.2688081-1-dvyukov@google.com>
Date:   Mon, 19 Sep 2022 06:25:33 +0200
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     tadeusz.struk@...aro.org
Cc:     gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] usb: mon: make mmapped memory read only

Hi Tadeusz,

Looking at places like these:
https://elixir.bootlin.com/linux/v6.0-rc5/source/drivers/infiniband/hw/qib/qib_file_ops.c#L736
https://elixir.bootlin.com/linux/v6.0-rc5/source/drivers/infiniband/hw/mlx5/main.c#L2088
I think we also need to remove VM_MAYWRITE, otherwise it's still
possible to turn it into a writable mapping with mprotect.

It's also probably better to return an error if VM_WRITE (or VM_EXEC?) is set
rather than silently fix it up.