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([2a01:e34:ed2f:f020:1ed:80a3:b8d6:f6d3]) by smtp.googlemail.com with ESMTPSA id f14sm9019461wmf.7.2021.03.14.03.48.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 14 Mar 2021 03:48:54 -0700 (PDT) Subject: Re: [PATCH v2 1/5] thermal/drivers/core: Use a char pointer for the cooling device name To: Ido Schimmel Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, lukasz.luba@arm.com, Jiri Pirko , Ido Schimmel , "David S. Miller" , Jakub Kicinski , Zhang Rui , Amit Kucheria , "open list:MELLANOX ETHERNET SWITCH DRIVERS" References: <20210312170316.3138-1-daniel.lezcano@linaro.org> From: Daniel Lezcano Message-ID: Date: Sun, 14 Mar 2021 11:48:53 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Ido, On 14/03/2021 10:53, Ido Schimmel wrote: > On Fri, Mar 12, 2021 at 06:03:12PM +0100, Daniel Lezcano wrote: >> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c >> index 996c038f83a4..9ef8090eb645 100644 >> --- a/drivers/thermal/thermal_core.c >> +++ b/drivers/thermal/thermal_core.c >> @@ -960,10 +960,7 @@ __thermal_cooling_device_register(struct device_node *np, [ ... ] >> /** >> @@ -1172,6 +1177,7 @@ void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev) >> device_del(&cdev->device); >> thermal_cooling_device_destroy_sysfs(cdev); >> put_device(&cdev->device); >> + kfree(cdev->type); >> } >> EXPORT_SYMBOL_GPL(thermal_cooling_device_unregister); > > I'm getting the following user-after-free with this patch [1]. Fixed by: > > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c > index 9ef8090eb645..c8d4010940ef 100644 > --- a/drivers/thermal/thermal_core.c > +++ b/drivers/thermal/thermal_core.c > @@ -1176,8 +1176,8 @@ void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev) > ida_simple_remove(&thermal_cdev_ida, cdev->id); > device_del(&cdev->device); > thermal_cooling_device_destroy_sysfs(cdev); > - put_device(&cdev->device); > kfree(cdev->type); > + put_device(&cdev->device); Indeed 'thermal_release' frees the cdev pointer and is called by put_device, then kfree use the pointer right after. Thanks for the fix -- Daniel -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog