[PATCH 3.11 096/131] dma: ste_dma40: don't dereference free:d descriptor
Luis Henriques
luis.henriques at canonical.com
Wed Mar 5 14:23:40 UTC 2014
3.11.10.6 -stable review patch. If anyone has any objections, please let me know.
------------------
From: Linus Walleij <linus.walleij at linaro.org>
commit e9baa9d9d520fb0e24cca671e430689de2d4a4b2 upstream.
It appears that in the DMA40 driver the DMA tasklet will very
often dereference memory for a descriptor just free:d from the
DMA40 slab. Nothing happens because no other part of the driver
has yet had a chance to claim this memory, but it's really
nasty to dereference free:d memory, so let's check the flag
before the descriptor is free and store it in a bool variable.
Reported-by: Dan Carpenter <dan.carpenter at oracle.com>
Signed-off-by: Linus Walleij <linus.walleij at linaro.org>
Signed-off-by: Vinod Koul <vinod.koul at intel.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
drivers/dma/ste_dma40.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c
index 5ab5880..637f4c5 100644
--- a/drivers/dma/ste_dma40.c
+++ b/drivers/dma/ste_dma40.c
@@ -1640,6 +1640,7 @@ static void dma_tasklet(unsigned long data)
struct d40_chan *d40c = (struct d40_chan *) data;
struct d40_desc *d40d;
unsigned long flags;
+ bool callback_active;
dma_async_tx_callback callback;
void *callback_param;
@@ -1667,6 +1668,7 @@ static void dma_tasklet(unsigned long data)
}
/* Callback to client */
+ callback_active = !!(d40d->txd.flags & DMA_PREP_INTERRUPT);
callback = d40d->txd.callback;
callback_param = d40d->txd.callback_param;
@@ -1689,7 +1691,7 @@ static void dma_tasklet(unsigned long data)
spin_unlock_irqrestore(&d40c->lock, flags);
- if (callback && (d40d->txd.flags & DMA_PREP_INTERRUPT))
+ if (callback_active && callback)
callback(callback_param);
return;
--
1.9.0
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