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Subject[PATCH 4.4 051/193] dmaengine: at_hdmac: fix potential NULL pointer dereference in atc_prep_dma_interleaved
Date
4.4-stable review patch.  If anyone has any objections, please let me know.

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

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


[ Upstream commit 62a277d43d47e74972de44d33bd3763e31992414 ]

_xt_ is being dereferenced before it is null checked, hence there is a
potential null pointer dereference.

Fix this by moving the pointer dereference after _xt_ has been null
checked.

This issue was detected with the help of Coccinelle.

Fixes: 4483320e241c ("dmaengine: Use Pointer xt after NULL check.")
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/dma/at_hdmac.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -716,7 +716,7 @@ atc_prep_dma_interleaved(struct dma_chan
unsigned long flags)
{
struct at_dma_chan *atchan = to_at_dma_chan(chan);
- struct data_chunk *first = xt->sgl;
+ struct data_chunk *first;
struct at_desc *desc = NULL;
size_t xfer_count;
unsigned int dwidth;
@@ -728,6 +728,8 @@ atc_prep_dma_interleaved(struct dma_chan
if (unlikely(!xt || xt->numf != 1 || !xt->frame_size))
return NULL;

+ first = xt->sgl;
+
dev_info(chan2dev(chan),
"%s: src=%pad, dest=%pad, numf=%d, frame_size=%d, flags=0x%lx\n",
__func__, &xt->src_start, &xt->dst_start, xt->numf,

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