diff mbox series

[5.9,265/391] dmaengine: dma-jz4780: Fix race in jz4780_dma_tx_status

Message ID 20201103203404.904108363@linuxfoundation.org
State Superseded
Headers show
Series None | expand

Commit Message

Greg Kroah-Hartman Nov. 3, 2020, 8:35 p.m. UTC 
From: Paul Cercueil <paul@crapouillou.net>

commit baf6fd97b16ea8f981b8a8b04039596f32fc2972 upstream.

The jz4780_dma_tx_status() function would check if a channel's cookie
state was set to 'completed', and if not, it would enter the critical
section. However, in that time frame, the jz4780_dma_chan_irq() function
was able to set the cookie to 'completed', and clear the jzchan->vchan
pointer, which was deferenced in the critical section of the first
function.

Fix this race by checking the channel's cookie state after entering the
critical function and not before.

Fixes: d894fc6046fe ("dmaengine: jz4780: add driver for the Ingenic JZ4780 DMA controller")
Cc: stable@vger.kernel.org # v4.0
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Reported-by: Artur Rojek <contact@artur-rojek.eu>
Tested-by: Artur Rojek <contact@artur-rojek.eu>
Link: https://lore.kernel.org/r/20201004140307.885556-1-paul@crapouillou.net
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/dma/dma-jz4780.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
diff mbox series

Patch

--- a/drivers/dma/dma-jz4780.c
+++ b/drivers/dma/dma-jz4780.c
@@ -639,11 +639,11 @@  static enum dma_status jz4780_dma_tx_sta
 	unsigned long flags;
 	unsigned long residue = 0;
 
+	spin_lock_irqsave(&jzchan->vchan.lock, flags);
+
 	status = dma_cookie_status(chan, cookie, txstate);
 	if ((status == DMA_COMPLETE) || (txstate == NULL))
-		return status;
-
-	spin_lock_irqsave(&jzchan->vchan.lock, flags);
+		goto out_unlock_irqrestore;
 
 	vdesc = vchan_find_desc(&jzchan->vchan, cookie);
 	if (vdesc) {
@@ -660,6 +660,7 @@  static enum dma_status jz4780_dma_tx_sta
 	    && jzchan->desc->status & (JZ_DMA_DCS_AR | JZ_DMA_DCS_HLT))
 		status = DMA_ERROR;
 
+out_unlock_irqrestore:
 	spin_unlock_irqrestore(&jzchan->vchan.lock, flags);
 	return status;
 }