linux-kernel - Re: [PATCH] rpmsg: virtio: fix possible double free in rpmsg

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Message-ID: <60d80bae-d229-0aa2-8c63-025754ab3438@gmail.com>
Date:   Tue, 26 Apr 2022 09:40:33 +0800
From:   Hangyu Hua <hbh25y@...il.com>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     bjorn.andersson@...aro.org, arnaud.pouliquen@...s.st.com,
        linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rpmsg: virtio: fix possible double free in rpmsg_probe()

On 2022/4/26 00:55, Mathieu Poirier wrote:
> On Mon, Apr 18, 2022 at 05:31:44PM +0800, Hangyu Hua wrote:
>> vch will be free in virtio_rpmsg_release_device() when
>> rpmsg_ns_register_device() fails. There is no need to call kfree() again.
>>
>> Fix this by changing error path from free_vch to free_ctrldev.
>>
>> Fixes: c486682ae1e2 ("rpmsg: virtio: Register the rpmsg_char device")
>> Signed-off-by: Hangyu Hua <hbh25y@...il.com>
>> ---
>>   drivers/rpmsg/virtio_rpmsg_bus.c | 4 +---
>>   1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
>> index 3ede25b1f2e4..603233f0686e 100644
>> --- a/drivers/rpmsg/virtio_rpmsg_bus.c
>> +++ b/drivers/rpmsg/virtio_rpmsg_bus.c
>> @@ -973,7 +973,7 @@ static int rpmsg_probe(struct virtio_device *vdev)
>>   
>>   		err = rpmsg_ns_register_device(rpdev_ns);
>>   		if (err)
>> -			goto free_vch;
> 
> Please add a comment that highlights where 'vch' will be free'd to avoid
> receiving patches that will introduce another kfree().  Same for your other
> patch.
> 
> In the next revision please use a cover letter and add Arnaud's patches to it.
> 
> Thanks,
> Mathieu
> 

Thanks! I will send a v2 later.

>> +			goto free_ctrldev;
>>   	}
>>   
>>   	/*
>> @@ -997,8 +997,6 @@ static int rpmsg_probe(struct virtio_device *vdev)
>>   
>>   	return 0;
>>   
>> -free_vch:
>> -	kfree(vch);
>>   free_ctrldev:
>>   	rpmsg_virtio_del_ctrl_dev(rpdev_ctrl);
>>   free_coherent:
>> -- 
>> 2.25.1
>>