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From:   Stefan Agner <stefan@agner.ch>
To:     hongxing.zhu@nxp.com, l.stach@pengutronix.de
Cc:     robin.murphy@arm.com, tpiepho@impinj.com, linux@armlinux.org.uk,
        leonard.crestez@nxp.com, andrew.smirnov@gmail.com,
        festevam@gmail.com, lorenzo.pieralisi@arm.com, bhelgaas@google.com,
        stefan@agner.ch, linux-pci@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2 1/2] pci: imx6: avoid dereferencing program counter from user mode
Date:   Tue,  4 Dec 2018 14:27:32 +0100
Message-Id: <20181204132733.14422-1-stefan@agner.ch>
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Sender: linux-kernel-owner@vger.kernel.org
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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@agner.ch>
---
 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