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dma: ste_dma40: don't dereference free:d descriptor 

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.

Cc: stable@vger.kernel.org
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Linus Walleij 2014-02-13 10:39:01 +01:00 committed by Vinod Koul
parent b28a960c42
commit e9baa9d9d5
1 changed files with 3 additions and 1 deletions
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4
drivers/dma/ste_dma40.c
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@ -1641,6 +1641,7 @@ 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;
@ -1668,6 +1669,7 @@ 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;
@ -1690,7 +1692,7 @@ 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;