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Re: [PATCH] xen-pciback: Fix pcistub_device ref leak in pcistub_get_gsi_from_sbdf()
- To: Wentao Liang <vulab@xxxxxxxxxxx>
- From: "Chen, Jiqian" <Jiqian.Chen@xxxxxxx>
- Date: Thu, 17 Sep 2026 06:01:51 +0000
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- Cc: "jgross@xxxxxxxx" <jgross@xxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>, "oleksandr_tyshchenko@xxxxxxxx" <oleksandr_tyshchenko@xxxxxxxx>, "Huang, Ray" <Ray.Huang@xxxxxxx>, "sstabellini@xxxxxxxxxx" <sstabellini@xxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, "stable@xxxxxxxxxxxxxxx" <stable@xxxxxxxxxxxxxxx>
- Delivery-date: Thu, 17 Sep 2026 06:02:39 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
- Thread-index: AQHdRf6GMogNWDJZT0qc64OaPhUu9bbSzYUA
- Thread-topic: [PATCH] xen-pciback: Fix pcistub_device ref leak in pcistub_get_gsi_from_sbdf()
On 9/17/26 01:11, Wentao Liang wrote:
> pcistub_get_gsi_from_sbdf() obtains the stub device with
> pcistub_device_find(), which returns it with its kref incremented, and
> returns psdev->gsi without dropping that reference again. The caller
> cannot release it either, so every lookup leaks one reference to the
> stub device.
>
> Release the reference after reading gsi.
>
> Fixes: 2fae6bb7be32 ("xen/privcmd: Add new syscall to get gsi from dev")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Wentao Liang <vulab@xxxxxxxxxxx>
Thanks.
Reviewed-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
> ---
> drivers/xen/xen-pciback/pci_stub.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/xen/xen-pciback/pci_stub.c
> b/drivers/xen/xen-pciback/pci_stub.c
> index 79a2b5dfd694..d1a335233aab 100644
> --- a/drivers/xen/xen-pciback/pci_stub.c
> +++ b/drivers/xen/xen-pciback/pci_stub.c
> @@ -234,13 +234,16 @@ static int pcistub_get_gsi_from_sbdf(unsigned int sbdf)
> int bus = PCI_BUS_NUM(sbdf);
> int slot = PCI_SLOT(sbdf);
> int func = PCI_FUNC(sbdf);
> + int gsi;
>
> psdev = pcistub_device_find(domain, bus, slot, func);
> -
> if (!psdev)
> return -ENODEV;
>
> - return psdev->gsi;
> + gsi = psdev->gsi;
> + pcistub_device_put(psdev);
> +
> + return gsi;
> }
> #endif
>
--
Best regards,
Jiqian Chen.
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