dmaengine: at_hdmac: fix potential NULL pointer dereference in atc_prep_dma_interleaved

[ 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>

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index a4c8f80..e2cec5b 100644 (file)
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -709,7 +709,7 @@ 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;
@@ -721,6 +721,8 @@ 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,