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

From: Stefan Agner
Date: Tue Dec 04 2018 - 08:27:41 EST


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>
---
drivers/pci/controller/dwc/pci-imx6.c | 10 ++++++++--
1 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,
unsigned int fsr, struct pt_regs *regs)
{
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;

/*
* If the instruction being executed was a read,
--
2.19.1