[PATCH v2 2/2] intel/pinctrl: check capability offset is between MMIO region

[Roger Pau Monne <roger.pau@citrix.com>]

When parsing the capability list make sure the offset is between the
MMIO region mapped in 'regs', or else the kernel hits a page fault.

Adding the check is harmless, and prevents buggy or broken systems
from crashing the kernel if the capability linked list is somehow
broken.

Fixes: 91d898e51e60 ('pinctrl: intel: Convert capability list to features')
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
Changes since v1:
 - Adjust commit message.
---
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Andy Shevchenko <andy@kernel.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-gpio@vger.kernel.org
---
 drivers/pinctrl/intel/pinctrl-intel.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/pinctrl/intel/pinctrl-intel.c b/drivers/pinctrl/intel/pinctrl-intel.c
index 59d13342caf6..d45a6994b2a3 100644
--- a/drivers/pinctrl/intel/pinctrl-intel.c
+++ b/drivers/pinctrl/intel/pinctrl-intel.c
@@ -1481,16 +1481,22 @@ static int intel_pinctrl_probe(struct platform_device *pdev,
 
 	for (i = 0; i < pctrl->ncommunities; i++) {
 		struct intel_community *community = &pctrl->communities[i];
+		struct resource *res;
 		void __iomem *regs;
+		size_t size;
 		u32 offset;
 		u32 value;
 
 		*community = pctrl->soc->communities[i];
 
-		regs = devm_platform_ioremap_resource(pdev, community->barno);
+		regs = devm_platform_get_and_ioremap_resource(pdev,
+							      community->barno,
+							      &res);
 		if (IS_ERR(regs))
 			return PTR_ERR(regs);
 
+		size = res->end - res->start;
+
 		/* Determine community features based on the revision */
 		value = readl(regs + REVID);
 		if (value == ~0u)
@@ -1521,6 +1527,12 @@ static int intel_pinctrl_probe(struct platform_device *pdev,
 				break;
 			}
 			offset = (value & CAPLIST_NEXT_MASK) >> CAPLIST_NEXT_SHIFT;
+			if (offset >= size) {
+				dev_err(&pdev->dev,
+					"wrong capability offset: %#x\n",
+					offset);
+				return -ENOENT;
+			}
 		} while (offset);
 
 		dev_dbg(&pdev->dev, "Community%d features: %#08x\n", i, community->features);
-- 
2.30.1