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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        "Gustavo A. R. Silva" <garsilva@embeddedor.com>,
        Patrice Chotard <patrice.chotard@st.com>,
        Mauro Carvalho Chehab <mchehab@s-opensource.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.4 74/97] media: c8sectpfe: fix potential NULL pointer dereference in c8sectpfe_timer_interrupt
Date:   Fri, 23 Mar 2018 10:55:01 +0100
Message-Id: <20180323094201.738568591@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Gustavo A. R. Silva" <garsilva@embeddedor.com>


[ Upstream commit baed3c4bc4c13de93e0dba0a26d601411ebcb389 ]

_channel_ is being dereferenced before it is null checked, hence there is a
potential null pointer dereference. Fix this by moving the pointer dereference
after _channel_ has been null checked.

This issue was detected with the help of Coccinelle.

Fixes: c5f5d0f99794 ("[media] c8sectpfe: STiH407/10 Linux DVB demux support")

Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Acked-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/media/platform/sti/c8sectpfe/c8sectpfe-core.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/media/platform/sti/c8sectpfe/c8sectpfe-core.c
+++ b/drivers/media/platform/sti/c8sectpfe/c8sectpfe-core.c
@@ -83,7 +83,7 @@ static void c8sectpfe_timer_interrupt(un
 static void channel_swdemux_tsklet(unsigned long data)
 {
 	struct channel_info *channel = (struct channel_info *)data;
-	struct c8sectpfei *fei = channel->fei;
+	struct c8sectpfei *fei;
 	unsigned long wp, rp;
 	int pos, num_packets, n, size;
 	u8 *buf;
@@ -91,6 +91,8 @@ static void channel_swdemux_tsklet(unsig
 	if (unlikely(!channel || !channel->irec))
 		return;
 
+	fei = channel->fei;
+
 	wp = readl(channel->irec + DMA_PRDS_BUSWP_TP(0));
 	rp = readl(channel->irec + DMA_PRDS_BUSRP_TP(0));