[PATCH AUTOSEL for 4.9 154/190] media: c8sectpfe: fix potential NULL pointer dereference in c8sectpfe_timer_interrupt

[Sasha Levin]

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

[ 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@xxxxxxxxxxxxxx>
Acked-by: Patrice Chotard <patrice.chotard@xxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 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 30c148b9d65e..06e2cfd09855 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