[PATCH] dmaengine: at_hdmac: fix potential NULL pointer dereference in atc_prep_dma_interleaved

From: Gustavo A. R. Silva
Date: Mon Nov 20 2017 - 09:28:22 EST


_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@xxxxxxxxxxxxxx>
---
drivers/dma/at_hdmac.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index fbab271..a861b5b 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -708,7 +708,7 @@ atc_prep_dma_interleaved(struct dma_chan *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;
@@ -720,6 +720,8 @@ atc_prep_dma_interleaved(struct dma_chan *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,
--
2.7.4