From: Matthias Kaehlcke <mka@chromium.org>
To: Douglas Anderson <dianders@chromium.org>
Cc: Felipe Balbi <balbi@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Sandeep Maheswaram <quic_c_sanm@quicinc.com>,
swboyd@chromium.org, Wesley Cheng <quic_wcheng@quicinc.com>,
robdclark@chromium.org, linux-arm-msm@vger.kernel.org,
Andy Gross <agross@kernel.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Wesley Cheng <wcheng@codeaurora.org>,
linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org
Subject: Re: [PATCH] usb: dwc3: dwc3-qcom: Avoid use-after-free when USB defers or unbinds
Date: Mon, 6 Dec 2021 16:29:53 -0800 [thread overview]
Message-ID: <Ya6rAVgZ+hSYNaVE@google.com> (raw)
In-Reply-To: <20211206152844.1.I411110cc99c1dd66b01aa9aa25651acf8ff55da1@changeid>
On Mon, Dec 06, 2021 at 03:28:47PM -0800, Douglas Anderson wrote:
> On sc7180-trogdor class devices with 'fw_devlink=permissive' and KASAN
> enabled, you'll see a Use-After-Free reported at bootup.
>
> The root of the problem is that dwc3_qcom_of_register_core() is adding
> a devm-allocated "tx-fifo-resize" property to its device tree node
> using of_add_property().
>
> The issue is that of_add_property() makes a _permanent_ addition to
> the device tree that lasts until reboot. That means allocating memory
> for the property using "devm" managed memory is a terrible idea since
> that memory will be freed upon probe deferral or device
> unbinding. Let's change to just allocate memory once and never free
> it. This sorta looks like a leak but isn't truly one, since only one
> property will be allocated per device tree node per boot.
>
> NOTE: one would think that perhaps it would be better to use
> of_remove_property() and then be able to free the property on device
> remove. That sounds good until you read the comments for
> of_remove_property(), which says that properties are never really
> removed and they're just moved to the side.
>
> Fixes: cefdd52fa045 ("usb: dwc3: dwc3-qcom: Enable tx-fifo-resize property by default")
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
next prev parent reply other threads:[~2021-12-07 0:29 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-06 23:28 [PATCH] usb: dwc3: dwc3-qcom: Avoid use-after-free when USB defers or unbinds Douglas Anderson
2021-12-07 0:02 ` Bjorn Andersson
2021-12-07 0:29 ` Matthias Kaehlcke [this message]
2021-12-07 0:37 ` Stephen Boyd
2021-12-07 0:48 ` Doug Anderson
2021-12-07 2:33 ` Bjorn Andersson
2021-12-07 17:46 ` Doug Anderson
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