PCI: dwc: Fix find_next_bit() usage

find_next_bit() takes a parameter of size long, and performs arithmetic
that assumes that the argument is of size long.

Therefore we cannot pass a u32, since this will cause find_next_bit()
to read outside the stack buffer and will produce the following print:
BUG: KASAN: stack-out-of-bounds in find_next_bit+0x38/0xb0

Fixes: 1b497e6493c4 ("PCI: dwc: Fix uninitialized variable in dw_handle_msi_irq()")
Tested-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Andrew Murray <andrew.murray@arm.com>
Acked-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 0f36a92..8615f15 100644 (file)
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -78,7 +78,8 @@ static struct msi_domain_info dw_pcie_msi_domain_info = {
 irqreturn_t dw_handle_msi_irq(struct pcie_port *pp)
 {
        int i, pos, irq;
-       u32 val, num_ctrls;
+       unsigned long val;
+       u32 status, num_ctrls;
        irqreturn_t ret = IRQ_NONE;
 
        num_ctrls = pp->num_vectors / MAX_MSI_IRQS_PER_CTRL;
@@ -86,14 +87,14 @@ irqreturn_t dw_handle_msi_irq(struct pcie_port *pp)
        for (i = 0; i < num_ctrls; i++) {
                dw_pcie_rd_own_conf(pp, PCIE_MSI_INTR0_STATUS +
                                        (i * MSI_REG_CTRL_BLOCK_SIZE),
-                                   4, &val);
-               if (!val)
+                                   4, &status);
+               if (!status)
                        continue;
 
                ret = IRQ_HANDLED;
+               val = status;
                pos = 0;
-               while ((pos = find_next_bit((unsigned long *) &val,
-                                           MAX_MSI_IRQS_PER_CTRL,
+               while ((pos = find_next_bit(&val, MAX_MSI_IRQS_PER_CTRL,
                                            pos)) != MAX_MSI_IRQS_PER_CTRL) {
                        irq = irq_find_mapping(pp->irq_domain,
                                               (i * MAX_MSI_IRQS_PER_CTRL) +