[PATCH] uio: uio_pci_generic_sva: fix double free of devm_kzalloc() memory

[PATCH] uio: uio_pci_generic_sva: fix double free of devm_kzalloc() memory

[Guangshuo Li]

uio_pci_sva allocates struct uio_pci_sva_dev with devm_kzalloc() in probe(), but then calls kfree(udev) both on the probe() error path (label out_free) and again in remove().
Because devm_kzalloc() allocations are devres-managed and are freed automatically when the device is detached, which also happens after a failing probe() and during driver unbind, the explicit kfree() can result in a double free. If probe() fails after devm_kzalloc(), the error path kfree(udev) frees the object, and devres cleanup will free it again when the core unwinds the partially bound device. On normal driver removal, remove() explicitly frees udev, and devres will free it again when the device is detached.

Fix by removing the manual kfree() calls and dropping the now-unused label.

Fixes: 3397c3cd859a2 ("uio: Add SVA support for PCI devices via uio_pci_generic_sva.c")
Cc: stable@vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
---
 drivers/uio/uio_pci_generic_sva.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/uio/uio_pci_generic_sva.c b/drivers/uio/uio_pci_generic_sva.c
index 4a46acd994a8..152201047334 100644
--- a/drivers/uio/uio_pci_generic_sva.c
+++ b/drivers/uio/uio_pci_generic_sva.c
@@ -129,15 +129,13 @@ static int probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	ret = devm_uio_register_device(&pdev->dev, &udev->info);
 	if (ret) {
 		dev_err(&pdev->dev, "Failed to register uio device\n");
-		goto out_free;
+		goto out_disable;
 	}
 
 	pci_set_drvdata(pdev, udev);
 
 	return 0;
 
-out_free:
-	kfree(udev);
 out_disable:
 	pci_disable_device(pdev);
 
@@ -150,7 +148,6 @@ static void remove(struct pci_dev *pdev)
 
 	pci_release_regions(pdev);
 	pci_disable_device(pdev);
-	kfree(udev);
 }
 
 static ssize_t pasid_show(struct device *dev,
-- 
2.43.0

Re: [PATCH] uio: uio_pci_generic_sva: fix double free of devm_kzalloc() memory

[Greg Kroah-Hartman]

On Wed, Feb 25, 2026 at 09:27:36PM +0800, Guangshuo Li wrote:
> uio_pci_sva allocates struct uio_pci_sva_dev with devm_kzalloc() in probe(), but then calls kfree(udev) both on the probe() error path (label out_free) and again in remove().
> Because devm_kzalloc() allocations are devres-managed and are freed automatically when the device is detached, which also happens after a failing probe() and during driver unbind, the explicit kfree() can result in a double free. If probe() fails after devm_kzalloc(), the error path kfree(udev) frees the object, and devres cleanup will free it again when the core unwinds the partially bound device. On normal driver removal, remove() explicitly frees udev, and devres will free it again when the device is detached.

Something went wrong here, please wrap your changelog text at 72
columns.

> Fix by removing the manual kfree() calls and dropping the now-unused label.
> 
> Fixes: 3397c3cd859a2 ("uio: Add SVA support for PCI devices via uio_pci_generic_sva.c")
> Cc: stable@vger.kernel.org
> Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>

How was this found and tested?

thanks,

greg k-h