linux-kernel - [PATCH] ARM: OMAP1: ams-delta: Fix possible use of uninitialized field

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Message-Id: <20181107213031.21650-1-jmkrzyszt@gmail.com>
Date:   Wed,  7 Nov 2018 22:30:31 +0100
From:   Janusz Krzysztofik <jmkrzyszt@...il.com>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Aaro Koskinen <aaro.koskinen@....fi>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Janusz Krzysztofik <jmkrzyszt@...il.com>
Subject: [PATCH] ARM: OMAP1: ams-delta: Fix possible use of uninitialized field

While playing with initialization order of modem device, it has been
discovered that under some circumstances (early console init, I
believe) its .pm() callback may be called before the
uart_port->private_data pointer is initialized from
plat_serial8250_port->private_data, resulting in NULL pointer
dereference.  Fix it by checking for uninitialized pointer before using
it in modem_pm().

Fixes: aabf31737a6a ("ARM: OMAP1: ams-delta: update the modem to use regulator API")
Signed-off-by: Janusz Krzysztofik <jmkrzyszt@...il.com>
---
 arch/arm/mach-omap1/board-ams-delta.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm/mach-omap1/board-ams-delta.c b/arch/arm/mach-omap1/board-ams-delta.c
index 1947bc63074e..17e0b386e1b2 100644
--- a/arch/arm/mach-omap1/board-ams-delta.c
+++ b/arch/arm/mach-omap1/board-ams-delta.c
@@ -764,6 +764,9 @@ static void modem_pm(struct uart_port *port, unsigned int state, unsigned old)
 	struct modem_private_data *priv = port->private_data;
 	int ret;
 
+	if (!priv)
+		return;
+
 	if (IS_ERR(priv->regulator))
 		return;
 
-- 
2.16.4