linux-kernel - [PATCH AUTOSEL for 4.4 079/101] media: c8sectpfe: fix potential NULL pointer dereference in c8sectpfe_timer

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Date:   Thu, 8 Mar 2018 05:02:07 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
CC:     "Gustavo A. R. Silva" <garsilva@...eddedor.com>,
        Mauro Carvalho Chehab <mchehab@...pensource.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.4 079/101] media: c8sectpfe: fix potential NULL
 pointer dereference in c8sectpfe_timer_interrupt

From: "Gustavo A. R. Silva" <garsilva@...eddedor.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@...eddedor.com>
Acked-by: Patrice Chotard <patrice.chotard@...com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@...pensource.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 drivers/media/platform/sti/c8sectpfe/c8sectpfe-core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/sti/c8sectpfe/c8sectpfe-core.c b/drivers/media/platform/sti/c8sectpfe/c8sectpfe-core.c
index 8490a65ae1c6..a43404cad3e3 100644
--- 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(unsigned long ac8sectpfei)
 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(unsigned long data)
 	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));
 
-- 
2.14.1