Re: [PATCH v3 9/9] pci: fix UAF when probe runs concurrent to dyn ID removal

["Gary Guo" <gary@garyguo.net>]

On Tue Jul 21, 2026 at 11:35 PM BST, Bjorn Helgaas wrote:
> On Mon, Jul 06, 2026 at 03:11:21PM +0100, Gary Guo wrote:
>> Dynamic IDs are only guaranteed to be valid when dynids.lock is held,
>> as remove_id_store can free the node. Thus, make a copy in
>> pci_match_device. Also, clarify that the id parameter is only valid during
>> probe.
>> 
>> Reported-by: Sashiko <sashiko-bot@kernel.org>
>> Link: https://lore.kernel.org/all/20260619170503.518F61F00A3A@smtp.kernel.org/
>> Fixes: 0994375e9614 ("PCI: add remove_id sysfs entry")
>> Signed-off-by: Gary Guo <gary@garyguo.net>
>> ---
>>  drivers/pci/pci-driver.c | 28 +++++++++++++++-------------
>>  include/linux/pci.h      |  1 +
>>  2 files changed, 16 insertions(+), 13 deletions(-)
>> 
>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>> index 64b308b6e61c..92c17c116de6 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -979,6 +979,7 @@ struct module;
>>   *		function returns zero when the driver chooses to
>>   *		take "ownership" of the device or an error code
>>   *		(negative number) otherwise.
>> + *		The pci_device_id parameter is only valid during probe.
>
> The probe function takes a pointer to a struct pci_device_id, so I
> think the requirement is that the struct pci_device_id only *needs* to
> be valid during .probe(), right, i.e., the PCI core probe path makes
> its own copy of the ID and doesn't retain the pointer after .probe()
> returns, right?
>
> I assume the caller determines the struct pci_device_id lifetime, and
> it could be forever.
>
> Could say something like:
>
>   The pci_device_id parameter only needs to be valid during probe.

As a contract on function parameter, the caller needs to guarantee that it lives
at least as long as documented (i.e. during the whole probe) and the callee
cannot assume that it will be valid beyond what's guaranteed.

How about:

    The pci_device_id parameter is only guaranteed to be valid during probe.

Best,
Gary