2024-05-29 13:25:56

by Yunseong Kim

Subject: [PATCH] xen/xenbus: handle pointer to NULL in alloc/free_pdev

From: Yunseong Kim <[email protected]>

Modify 'alloc_pdev()' to set 'pdev->xdev' to NULL
if 'xen_pcibk_init_devices()' fails. This ensures that 'pdev->xdev' does
not point to 'xdev' when 'pdev' is freed.
And modify 'free_pdev()' to set 'pdev' to NULL.

Signed-off-by: Yunseong Kim <[email protected]>
---
drivers/xen/xen-pciback/xenbus.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
index b11e401f1b1e..f1709b8e284a 100644
--- a/drivers/xen/xen-pciback/xenbus.c
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -54,6 +54,7 @@ static struct xen_pcibk_device *alloc_pdev(struct xenbus_device *xdev)
INIT_WORK(&pdev->op_work, xen_pcibk_do_op);

if (xen_pcibk_init_devices(pdev)) {
+ pdev->xdev = NULL;
kfree(pdev);
pdev = NULL;
}
@@ -102,6 +103,7 @@ static void free_pdev(struct xen_pcibk_device *pdev)
pdev->xdev = NULL;

kfree(pdev);
+ pdev = NULL;
}

static int xen_pcibk_do_attach(struct xen_pcibk_device *pdev, int gnt_ref,
--
2.34.1

2024-05-29 13:28:56

by Jürgen Groß

Subject: Re: [PATCH] xen/xenbus: handle pointer to NULL in alloc/free_pdev

On 29.05.24 15:19, [email protected] wrote:
> From: Yunseong Kim <[email protected]>
>
> Modify 'alloc_pdev()' to set 'pdev->xdev' to NULL
> if 'xen_pcibk_init_devices()' fails. This ensures that 'pdev->xdev' does
> not point to 'xdev' when 'pdev' is freed.
> And modify 'free_pdev()' to set 'pdev' to NULL.
>
> Signed-off-by: Yunseong Kim <[email protected]>
> ---
> drivers/xen/xen-pciback/xenbus.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
> index b11e401f1b1e..f1709b8e284a 100644
> --- a/drivers/xen/xen-pciback/xenbus.c
> +++ b/drivers/xen/xen-pciback/xenbus.c
> @@ -54,6 +54,7 @@ static struct xen_pcibk_device *alloc_pdev(struct xenbus_device *xdev)
> INIT_WORK(&pdev->op_work, xen_pcibk_do_op);
>
> if (xen_pcibk_init_devices(pdev)) {
> + pdev->xdev = NULL;
> kfree(pdev);
> pdev = NULL;
> }
> @@ -102,6 +103,7 @@ static void free_pdev(struct xen_pcibk_device *pdev)
> pdev->xdev = NULL;
>
> kfree(pdev);
> + pdev = NULL;
> }
>
> static int xen_pcibk_do_attach(struct xen_pcibk_device *pdev, int gnt_ref,

NAK!

Please stop that nonsense. NULL-ing pointers which have no chance to be used any
more is just adding code for no purpose at all.

Please don't send other iterations of this patch. You are wasting review
bandwidth.


Juergen