linux-kernel - [PATCH AUTOSEL 4.19] pwm: Fix double shift bug

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Message-ID: <20231115034230.1243196-1-sashal@kernel.org>
Date:   Tue, 14 Nov 2023 22:42:28 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Dan Carpenter <dan.carpenter@...aro.org>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Sam Protsenko <semen.protsenko@...aro.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Sasha Levin <sashal@...nel.org>, linux-pwm@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19] pwm: Fix double shift bug

From: Dan Carpenter <dan.carpenter@...aro.org>

[ Upstream commit d27abbfd4888d79dd24baf50e774631046ac4732 ]

These enums are passed to set/test_bit().  The set/test_bit() functions
take a bit number instead of a shifted value.  Passing a shifted value
is a double shift bug like doing BIT(BIT(1)).  The double shift bug
doesn't cause a problem here because we are only checking 0 and 1 but
if the value was 5 or above then it can lead to a buffer overflow.

Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Reviewed-by: Sam Protsenko <semen.protsenko@...aro.org>
Signed-off-by: Thierry Reding <thierry.reding@...il.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 include/linux/pwm.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index bd7d611d63e91..c6e981035c3fd 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -44,8 +44,8 @@ struct pwm_args {
 };
 
 enum {
-	PWMF_REQUESTED = 1 << 0,
-	PWMF_EXPORTED = 1 << 1,
+	PWMF_REQUESTED = 0,
+	PWMF_EXPORTED = 1,
 };
 
 /*
-- 
2.42.0