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[93.173.93.237]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-43ced9a4b19sm68553345e9.29.2025.03.10.06.46.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 10 Mar 2025 06:46:31 -0700 (PDT) Message-ID: <4cd852e0-6d6d-fcb4-6e4c-e6f861f429db@outbound.gmail.com> Date: Mon, 10 Mar 2025 15:45:46 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 From: Eli Billauer Subject: Re: [PATCH] char: xillybus: Fix error handling in xillybus_init_chrdev() To: Ma Ke , arnd@arndb.de, gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, stable@vger.kernel.org References: <20250310022811.182553-1-make24@iscas.ac.cn> Content-Language: en-US In-Reply-To: <20250310022811.182553-1-make24@iscas.ac.cn> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hello, Thanks for your patch. However, as far as I understand, applying it will cause a Use After Free (UAF) error by cdev_del(), as the call to kobject_put() unwinds the memory allocation made by cdev_alloc(). Or have I missed something? Regards, Eli On 10/03/2025 4:28, Ma Ke wrote: > After cdev_alloc() succeed and cdev_add() failed, call cdev_del() to > remove unit->cdev from the system properly. > > Found by code review. > > Cc: stable@vger.kernel.org > Fixes: 8cb5d216ab33 ("char: xillybus: Move class-related functions to new xillybus_class.c") > Signed-off-by: Ma Ke > --- > drivers/char/xillybus/xillybus_class.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/char/xillybus/xillybus_class.c b/drivers/char/xillybus/xillybus_class.c > index c92a628e389e..045e125ec423 100644 > --- a/drivers/char/xillybus/xillybus_class.c > +++ b/drivers/char/xillybus/xillybus_class.c > @@ -105,7 +105,7 @@ int xillybus_init_chrdev(struct device *dev, > dev_err(dev, "Failed to add cdev.\n"); > /* kobject_put() is normally done by cdev_del() */ > kobject_put(&unit->cdev->kobj); > - goto unregister_chrdev; > + goto err_cdev; > } > > for (i = 0; i < num_nodes; i++) { > @@ -157,6 +157,7 @@ int xillybus_init_chrdev(struct device *dev, > device_destroy(&xillybus_class, MKDEV(unit->major, > i + unit->lowest_minor)); > > +err_cdev: > cdev_del(unit->cdev); > > unregister_chrdev: