On 13/06/2019 07:54, Dan Carpenter wrote:
Hello Tomasz Nowicki,
The patch 4bf2efd26d76: "ACPI: Add new IORT functions to support MSI
domain handling" from Sep 12, 2016, leads to the following static
checker warning:
drivers/acpi/arm64/iort.c:628 iort_dev_find_its_id()
warn: array off by one? 'its->identifiers[idx]'
drivers/acpi/arm64/iort.c
589 /**
590 * iort_dev_find_its_id() - Find the ITS identifier for a device
591 * @dev: The device.
592 * @req_id: Device's requester ID
593 * @idx: Index of the ITS identifier list.
594 * @its_id: ITS identifier.
595 *
596 * Returns: 0 on success, appropriate error value otherwise
597 */
598 static int iort_dev_find_its_id(struct device *dev, u32 req_id,
599 unsigned int idx, int *its_id)
600 {
601 struct acpi_iort_its_group *its;
602 struct acpi_iort_node *node;
603
604 node = iort_find_dev_node(dev);
605 if (!node)
606 return -ENXIO;
607
608 node = iort_node_map_id(node, req_id, NULL, IORT_MSI_TYPE);
609 if (!node)
610 return -ENXIO;
611
612 /* Move to ITS specific data */
613 its = (struct acpi_iort_its_group *)node->node_data;
614 if (idx > its->its_count) {
^^^^^^^^^^^^^^^^^^^^
I wasn't able to find any information about how its->its_count is set
but it looks to me that is off by one.
its->count is read directly from the firmware table. Currently it seems
this condition can never be hit anyway, since this is only ever called
with idx == 0. TBH I can't really see how the code could evolve such
that this check should ever be necessary (i.e. it makes no sense for
callers to pull idx values out if thin air, so they'd presumably end up
being derived from its->count in the first place), but if we are going
to have it then I agree it should be ">=".
Robin.
615 dev_err(dev, "requested ITS ID index [%d] is greater than available [%d]\n",
616 idx, its->its_count);
617 return -ENXIO;
618 }
619
620 *its_id = its->identifiers[idx];
621 return 0;
622 }
regards,
dan carpenter
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