[PATCH 5.4 134/203] PCI: dwc: Fix find_next_bit() usage

Greg Kroah-Hartman
2020-01-16T23:24:33Z

From: Niklas Cassel <niklas.cassel@linaro.org>

commit 1137e61dcb99f7f8b54e77ed83f68b5b485a3e34 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/pci/controller/dwc/pcie-designware-host.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

--- 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_ms
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 pci
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) +