linux-kernel - [PATCH 3/3] pinctrl: single: fix infinite loop caused by bad mask

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Date:	Thu, 9 Jan 2014 14:50:29 +0200
From:	Tomi Valkeinen <tomi.valkeinen@...com>
To:	<linux-kernel@...r.kernel.org>,
	Linus Walleij <linus.walleij@...aro.org>
CC:	Tomi Valkeinen <tomi.valkeinen@...com>
Subject: [PATCH 3/3] pinctrl: single: fix infinite loop caused by bad mask

commit 4e7e8017a80e1 (pinctrl: pinctrl-single:
enhance to configure multiple pins of different modules) improved
support for pinctrl-single,bits option, but also caused a regression
in parsing badly configured mask data.

If the masks in DT data are not quite right,
pcs_parse_bits_in_pinctrl_entry() can end up in an infinite loop,
trashing memory at the same time.

Add a check to verify that each loop actually removes bits from the
'mask', so that the loop can eventually end.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...com>
Acked-by: Tony Lindgren <tony@...mide.com>
---
 drivers/pinctrl/pinctrl-single.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/pinctrl/pinctrl-single.c b/drivers/pinctrl/pinctrl-single.c
index 174f4c50cd77..de6459628b4f 100644
--- a/drivers/pinctrl/pinctrl-single.c
+++ b/drivers/pinctrl/pinctrl-single.c
@@ -1318,6 +1318,14 @@ static int pcs_parse_bits_in_pinctrl_entry(struct pcs_device *pcs,
 			mask_pos = ((pcs->fmask) << (bit_pos - 1));
 			val_pos = val & mask_pos;
 			submask = mask & mask_pos;
+
+			if ((mask & mask_pos) == 0) {
+				dev_err(pcs->dev,
+					"Invalid mask for %s at 0x%x\n",
+					np->name, offset);
+				break;
+			}
+
 			mask &= ~mask_pos;
 
 			if (submask != mask_pos) {
-- 
1.8.3.2

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