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[2a02:8389:41cf:e200:a034:352b:6ceb:bf05]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-37d4b6bd3e7sm8582567f8f.39.2024.10.13.05.55.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 13 Oct 2024 05:55:33 -0700 (PDT) Message-ID: <4c190f41-eac4-4dfa-8667-368f57b9f445@gmail.com> Date: Sun, 13 Oct 2024 14:55:30 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] staging: vchiq_arm: Fix missing refcount decrement in error path for fw_node To: Umang Jain , Florian Fainelli , Broadcom internal kernel review list , Greg Kroah-Hartman , Stefan Wahren , Laurent Pinchart Cc: linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20241013-vchiq_arm-of_node_put-v1-1-f72b2a6e47d0@gmail.com> Content-Language: en-US, de-AT From: Javier Carrasco In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 13/10/2024 13:36, Umang Jain wrote: > Hi Javier, > > Thank you for the patch. > > On 13/10/24 4:12 pm, Javier Carrasco wrote: >> An error path was introduced without including the required call to >> of_node_put() to decrement the node's refcount and avoid leaking memory. >> If the call to kzalloc() for 'mgmt' fails, the probe returns without >> decrementing the refcount. >> >> Use the automatic cleanup facility to fix the bug and protect the code >> against new error paths where the call to of_node_put() might be missing >> again. >> >> Cc: stable@vger.kernel.org >> Fixes: 1c9e16b73166 ("staging: vc04_services: vchiq_arm: Split driver >> static and runtime data") >> Signed-off-by: Javier Carrasco >> --- >>   drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c | 6 + >> +---- >>   1 file changed, 2 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/ >> vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/ >> vchiq_arm.c >> index 27ceaac8f6cc..792cf3a807e1 100644 >> --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c >> +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c >> @@ -1332,7 +1332,8 @@ MODULE_DEVICE_TABLE(of, vchiq_of_match); >>     static int vchiq_probe(struct platform_device *pdev) >>   { >> -    struct device_node *fw_node; >> +    struct device_node *fw_node __free(device_node) = >> +        of_find_compatible_node(NULL, NULL, "raspberrypi,bcm2835- >> firmware"); > > How about : > > +    struct device_node *fw_node __free(device_node) = NULL; > >>       const struct vchiq_platform_info *info; >>       struct vchiq_drv_mgmt *mgmt; >>       int ret; >> @@ -1341,8 +1342,6 @@ static int vchiq_probe(struct platform_device >> *pdev) >>       if (!info) >>           return -EINVAL; >>   -    fw_node = of_find_compatible_node(NULL, NULL, >> -                      "raspberrypi,bcm2835-firmware"); > > And undo this (i.e. keep the of_find_compatible_node() call here > > This helps with readability as there is a NULL check just after this. >>       if (!fw_node) { >>           dev_err(&pdev->dev, "Missing firmware node\n"); >>           return -ENOENT; >> @@ -1353,7 +1352,6 @@ static int vchiq_probe(struct platform_device >> *pdev) >>           return -ENOMEM; >>         mgmt->fw = devm_rpi_firmware_get(&pdev->dev, fw_node); >> -    of_node_put(fw_node); > > And this change remains the same. >>       if (!mgmt->fw) >>           return -EPROBE_DEFER; >>   >> --- >> base-commit: d61a00525464bfc5fe92c6ad713350988e492b88 >> change-id: 20241013-vchiq_arm-of_node_put-60a5eaaafd70 >> >> Best regards, > Hi Umang, Sure, I am fine with that too. Depending on the maintainer, the preferred approach varies: a single initialization at the top whenever possible, a declaration right before its first usage (not my favorite), or a NULL initialization first. I will send a v2 with the latter i.e. what you suggested, as it keeps everything more similar to what it used to be. Thanks and best regards, Javier Carrasco