Messages in this thread Patch in this message | | | From | Luis Henriques <> | Subject | [PATCH 3.5 43/62] dma: ste_dma40: don't dereference free:d descriptor | Date | Wed, 5 Mar 2014 14:36:47 +0000 |
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3.5.7.32 -stable review patch. If anyone has any objections, please let me know.
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From: Linus Walleij <linus.walleij@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@oracle.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Vinod Koul <vinod.koul@intel.com> Signed-off-by: Luis Henriques <luis.henriques@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 aec952f..b138bc4 100644 --- a/drivers/dma/ste_dma40.c +++ b/drivers/dma/ste_dma40.c @@ -1412,6 +1412,7 @@ 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; @@ -1435,6 +1436,7 @@ 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; @@ -1459,7 +1461,7 @@ 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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