This is a note to let you know that I've just added the patch titled
dma: ste_dma40: don't dereference free:d descriptor
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dma-ste_dma40-don-t-dereference-free-d-descriptor.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e9baa9d9d520fb0e24cca671e430689de2d4a4b2 Mon Sep 17 00:00:00 2001
From: Linus Walleij <linus.walleij@xxxxxxxxxx>
Date: Thu, 13 Feb 2014 10:39:01 +0100
Subject: dma: ste_dma40: don't dereference free:d descriptor
From: Linus Walleij <linus.walleij@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Vinod Koul <vinod.koul@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -1409,6 +1409,7 @@ 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;
@@ -1432,6 +1433,7 @@ 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;
@@ -1456,7 +1458,7 @@ 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;
Patches currently in stable-queue which might be from linus.walleij@xxxxxxxxxx are
queue-3.4/dma-ste_dma40-don-t-dereference-free-d-descriptor.patch
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