3.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Linus Walleij <linus.wall...@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.carpen...@oracle.com>
Signed-off-by: Linus Walleij <linus.wall...@linaro.org>
Signed-off-by: Vinod Koul <vinod.k...@intel.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
drivers/dma/ste_dma40.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/dma/ste_dma40.c
+++ b/drivers/dma/ste_dma40.c
@@ -1587,6 +1587,7 @@ static void dma_tasklet(unsigned long da
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;
@@ -1614,6 +1615,7 @@ static void dma_tasklet(unsigned long da
}
/* Callback to client */
+ callback_active = !!(d40d->txd.flags & DMA_PREP_INTERRUPT);
callback = d40d->txd.callback;
callback_param = d40d->txd.callback_param;
@@ -1636,7 +1638,7 @@ static void dma_tasklet(unsigned long da
spin_unlock_irqrestore(&d40c->lock, flags);
- if (callback && (d40d->txd.flags & DMA_PREP_INTERRUPT))
+ if (callback_active && callback)
callback(callback_param);
return;
--
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