Re: [PATCH v2 1/2] pci: imx6: avoid dereferencing program counter from user mode

[Lucas Stach]

Am Dienstag, den 04.12.2018, 14:27 +0100 schrieb Stefan Agner:
> The custom fault handler is currently only meant to handle kernel
> mode bus faults. Exit in case the abort happened in user mode.
> 
> Signed-off-by: Stefan Agner <stefan@xxxxxxxx>

Reviewed-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>

> ---
> Âdrivers/pci/controller/dwc/pci-imx6.c | 10 ++++++++--
> Â1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 69f86234f7c0..54a29e441303 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -270,8 +270,14 @@ static int imx6q_pcie_abort_handler(unsigned long addr,
> Â		unsigned int fsr, struct pt_regs *regs)
> Â{
> Â	unsigned long pc = instruction_pointer(regs);
> -	unsigned long instr = *(unsigned long *)pc;
> -	int reg = (instr >> 12) & 15;
> +	unsigned long instr;
> +	int reg;
> +
> +	if (user_mode(regs))
> +		return 1;
> +
> +	instr = *(unsigned long *)pc;
> +	reg = (instr >> 12) & 15;
> Â
> Â	/*
> Â	Â* If the instruction being executed was a read,