On Fri, Jul 12, 2019 at 03:26:11PM +0200, Lucas Stach wrote:
> Find_next_bit works on a long type, which causes a OOB read on the
> u32 input when used on ARM64.
s/Find_next_bit/find_next_bit()/ so it's obviously a function name and
we can directly grep for it (in subject also, and capitalize "Avoid").
Please spell out "OOB"; I *assume* that means "out of bounds"?
> Signed-off-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> ---
> drivers/pci/controller/dwc/pcie-designware-host.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 77db32529319..81a2139d68d6 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -78,15 +78,16 @@ 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;
> + u32 num_ctrls;
> irqreturn_t ret = IRQ_NONE;
> + unsigned long val;
>
> num_ctrls = pp->num_vectors / MAX_MSI_IRQS_PER_CTRL;
>
> 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);
> + 4, (u32 *)&val);
I agree that the "val" we pass to find_next_bit() needs to be an
"unsigned long", so I like that part.
It's not completely obvious to me that it's safe to cast "val" to
"u32 *" here; does that do the right thing regardless of byte order?
Doing something like:
u32 status;
unsigned long val;
dw_pcie_rd_own_conf(..., &status);
val = status;
find_next_bit(&val, ...);
would be more obvious to me.
> if (!val)
> continue;
>
> --
> 2.20.1
>
