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SubjectRe: [PATCH] dmaengine: at_hdmac: fix potential NULL pointer dereference in atc_prep_dma_interleaved
On Mon, Nov 20, 2017 at 08:28:14AM -0600, Gustavo A. R. Silva wrote:
> _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>

Thanks

> ---
> 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
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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