[PATCH] uio: uio_pci_generic_sva: reject multiple opens

[Avi Weiss <thnkslprpt@gmail.com>]

uio_pci_sva_open() stores an SVA binding handle in device-wide state.
A second open from another address space overwrites that handle. Closing
the two descriptors then unbinds the second handle twice and leaves the
first binding active.

Reject another open while a binding is active and clear the handle on
release. UIO core already serializes the callbacks under info_lock.

Fixes: 3397c3cd859a ("uio: Add SVA support for PCI devices via uio_pci_generic_sva.c")
Signed-off-by: Avi Weiss <thnkslprpt@gmail.com>
---
 drivers/uio/uio_pci_generic_sva.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/uio/uio_pci_generic_sva.c b/drivers/uio/uio_pci_generic_sva.c
index d05ef77f7e322..fedf54e82f270 100644
--- a/drivers/uio/uio_pci_generic_sva.c
+++ b/drivers/uio/uio_pci_generic_sva.c
@@ -32,6 +32,9 @@ static int uio_pci_sva_open(struct uio_info *info, struct inode *inode)
 	if (!udev || !udev->pdev)
 		return -ENODEV;
 
+	if (udev->sva_handle)
+		return -EBUSY;
+
 	domain = iommu_get_domain_for_dev(&udev->pdev->dev);
 	if (domain)
 		iommu_detach_device(domain, &udev->pdev->dev);
@@ -55,6 +58,7 @@ static int uio_pci_sva_release(struct uio_info *info, struct inode *inode)
 		return -ENODEV;
 
 	iommu_sva_unbind_device(udev->sva_handle);
+	udev->sva_handle = NULL;
 
 	return 0;
 }

base-commit: 65ba8f34ec886ec72b2c07ddc8cf3d815c32869d
-- 
2.43.0