Re: [PATCH] xen/pciback: Fix conf_space read/write overlap check.

From: Boris Ostrovsky
Date: Tue Jun 21 2016 - 11:54:10 EST


On 06/21/2016 10:37 AM, Andrey Grodzovsky wrote:
> Current overlap check is evaluating to false a case where a filter field
> is fully contained (proper subset) of a r/w request.
> This change applies classical overlap check instead to include
> all the scenarios.
>
> Related to https://www.mail-archive.com/xen-devel@xxxxxxxxxxxxx/msg72174.html
>
> Cc: Jan Beulich <JBeulich@xxxxxxxx>
> Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Andrey Grodzovsky <andrey2805@xxxxxxxxx>

+ David and Juergen (maintainers) and kernel list.

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>


> ---
> drivers/xen/xen-pciback/conf_space.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/xen/xen-pciback/conf_space.c b/drivers/xen/xen-pciback/conf_space.c
> index 8e67336..6a25533 100644
> --- a/drivers/xen/xen-pciback/conf_space.c
> +++ b/drivers/xen/xen-pciback/conf_space.c
> @@ -183,8 +183,7 @@ int xen_pcibk_config_read(struct pci_dev *dev, int offset, int size,
> field_start = OFFSET(cfg_entry);
> field_end = OFFSET(cfg_entry) + field->size;
>
> - if ((req_start >= field_start && req_start < field_end)
> - || (req_end > field_start && req_end <= field_end)) {
> + if (req_end > field_start && field_end > req_start) {
> err = conf_space_read(dev, cfg_entry, field_start,
> &tmp_val);
> if (err)
> @@ -230,8 +229,7 @@ int xen_pcibk_config_write(struct pci_dev *dev, int offset, int size, u32 value)
> field_start = OFFSET(cfg_entry);
> field_end = OFFSET(cfg_entry) + field->size;
>
> - if ((req_start >= field_start && req_start < field_end)
> - || (req_end > field_start && req_end <= field_end)) {
> + if (req_end > field_start && field_end > req_start) {
> tmp_val = 0;
>
> err = xen_pcibk_config_read(dev, field_start,