| From e9baa9d9d520fb0e24cca671e430689de2d4a4b2 Mon Sep 17 00:00:00 2001 |
| From: Linus Walleij <linus.walleij@linaro.org> |
| Date: Thu, 13 Feb 2014 10:39:01 +0100 |
| Subject: dma: ste_dma40: don't dereference free:d descriptor |
| |
| 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: Greg Kroah-Hartman <gregkh@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 |
| @@ -1641,6 +1641,7 @@ 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; |
| |
| @@ -1668,6 +1669,7 @@ 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; |
| |
| @@ -1690,7 +1692,7 @@ 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; |