This is a note to let you know that I've just added the patch titled

dmaengine: stm32-dma: Fix null pointer dereference in stm32_dma_tx_status

to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: dmaengine-stm32-dma-fix-null-pointer-dereference-in-stm32_dma_tx_status.patch and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Wed Dec 6 17:39:55 CET 2017

From: M'boumba Cedric Madianga cedric.madianga@gmail.com Date: Tue, 13 Dec 2016 14:40:46 +0100 Subject: dmaengine: stm32-dma: Fix null pointer dereference in stm32_dma_tx_status

From: M'boumba Cedric Madianga cedric.madianga@gmail.com

[ Upstream commit 57b5a32135c813f2ab669039fb4ec16b30cb3305 ]

chan->desc is always set to NULL when a DMA transfer is complete. As a DMA transfer could be complete during the call of stm32_dma_tx_status, we need to be sure that chan->desc is not NULL before using this variable to avoid a null pointer deference issue.

Signed-off-by: M'boumba Cedric Madianga cedric.madianga@gmail.com Reviewed-by: Ludovic BARRE ludovic.barre@st.com Signed-off-by: Vinod Koul vinod.koul@intel.com Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/dma/stm32-dma.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-)

--- a/drivers/dma/stm32-dma.c +++ b/drivers/dma/stm32-dma.c @@ -884,7 +884,7 @@ static enum dma_status stm32_dma_tx_stat struct virt_dma_desc *vdesc; enum dma_status status; unsigned long flags; - u32 residue; + u32 residue = 0;

status = dma_cookie_status(c, cookie, state); if ((status == DMA_COMPLETE) || (!state)) @@ -892,16 +892,12 @@ static enum dma_status stm32_dma_tx_stat

spin_lock_irqsave(&chan->vchan.lock, flags); vdesc = vchan_find_desc(&chan->vchan, cookie); - if (cookie == chan->desc->vdesc.tx.cookie) { + if (chan->desc && cookie == chan->desc->vdesc.tx.cookie) residue = stm32_dma_desc_residue(chan, chan->desc, chan->next_sg); - } else if (vdesc) { + else if (vdesc) residue = stm32_dma_desc_residue(chan, to_stm32_dma_desc(vdesc), 0); - } else { - residue = 0; - } - dma_set_residue(state, residue);

spin_unlock_irqrestore(&chan->vchan.lock, flags);

Patches currently in stable-queue which might be from cedric.madianga@gmail.com are

queue-4.9/dmaengine-stm32-dma-fix-null-pointer-dereference-in-stm32_dma_tx_status.patch queue-4.9/dmaengine-stm32-dma-set-correct-args-number-for-dma-request-from-dt.patch