linux-kernel - Re: [PATCH v2 1/3] PCI/sysfs: Fix null pointer dereference during hotplug

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Message-ID: <73f351b9-5355-4111-9d29-9b3b906cb651@huawei.com>
Date: Tue, 30 Dec 2025 11:40:26 +0800
From: duziming <duziming2@...wei.com>
To: Bjorn Helgaas <helgaas@...nel.org>
CC: <bhelgaas@...gle.com>, <jbarnes@...tuousgeek.org>, <chrisw@...hat.com>,
	<alex.williamson@...hat.com>, <linux-pci@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <liuyongqiang13@...wei.com>
Subject: Re: [PATCH v2 1/3] PCI/sysfs: Fix null pointer dereference during
 hotplug


在 2025/12/30 1:31, Bjorn Helgaas 写道:
> On Wed, Dec 24, 2025 at 05:27:17PM +0800, Ziming Du wrote:
>> During the concurrent process of creating and rescanning in VF, the
>> resource files for the same pci_dev may be created twice. The second
>> creation attempt fails, resulting the res_attr in pci_dev to kfree(),
>> but the pointer is not set to NULL. This will subsequently lead to
>> dereferencing a null pointer when removing the device.
>>
>> When we perform the following operation:
>>    echo $vfcount > /sys/class/net/"$pfname"/device/sriov_numvfs &
> Is the value of $vfcount relevant here?  Can you use the actual values
> here instead of the variables so this is more useful to others?

In fact, we directly use sriov_totalvfs here. In my opinion, the larger 
this value is,

the more likely it is to cause the issue.

>>    sleep 0.5
>>    echo 1 > /sys/bus/pci/rescan
>>    pci_remove "$pfname"
>> system will crash as follows: