From mboxrd@z Thu Jan 1 00:00:00 1970 From: Philipp Zabel Subject: Re: [PATCH] reset: Fix potential use-after-free in __of_reset_control_get() Date: Mon, 08 Oct 2018 14:56:15 +0200 Message-ID: <1539003375.11512.19.camel@pengutronix.de> References: <20181008111435.25994-1-geert+renesas@glider.be> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20181008111435.25994-1-geert+renesas@glider.be> Sender: linux-kernel-owner@vger.kernel.org To: Geert Uytterhoeven Cc: linux-kernel@vger.kernel.org, devicetree@vger.kernel.org List-Id: devicetree@vger.kernel.org Hi Geert, On Mon, 2018-10-08 at 13:14 +0200, Geert Uytterhoeven wrote: > Calling of_node_put() decreases the reference count of a device tree > object, and may free some data. > > However, the of_phandle_args structure embedding it is passed to > reset_controller_dev.of_xlate() after that, so it may still be accessed. > > Move the call to of_node_put() down to fix this. > > Signed-off-by: Geert Uytterhoeven > --- > drivers/reset/core.c | 15 ++++++++------- > 1 file changed, 8 insertions(+), 7 deletions(-) > > diff --git a/drivers/reset/core.c b/drivers/reset/core.c > index 225e34c56b94a2e3..bc9df10d31b4bae1 100644 > --- a/drivers/reset/core.c > +++ b/drivers/reset/core.c > @@ -496,27 +496,28 @@ struct reset_control *__of_reset_control_get(struct device_node *node, > break; > } > } > - of_node_put(args.np); > > if (!rcdev) { > - mutex_unlock(&reset_list_mutex); > - return ERR_PTR(-EPROBE_DEFER); > + rstc = ERR_PTR(-EPROBE_DEFER); > + goto out; > } > > if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) { > - mutex_unlock(&reset_list_mutex); > - return ERR_PTR(-EINVAL); > + rstc = ERR_PTR(-EINVAL); > + goto out; > } > > rstc_id = rcdev->of_xlate(rcdev, &args); > if (rstc_id < 0) { > - mutex_unlock(&reset_list_mutex); > - return ERR_PTR(rstc_id); > + rstc = ERR_PTR(rstc_id); > + goto out; > } > > /* reset_list_mutex also protects the rcdev's reset_control list */ > rstc = __reset_control_get_internal(rcdev, rstc_id, shared); > > +out: > + of_node_put(args.np); > mutex_unlock(&reset_list_mutex); Thank you for the patch. I'd like to move of_node_put after mutex_unlock for symmetry. If you agree, I can switch the two when applying. regards Philipp