[alsa-devel] [patch] ASoC: dapm: using freed pointer in dapm_kcontrol_add_widget()

Lars-Peter Clausen lars at metafoo.de
Wed Jul 31 20:33:03 CEST 2013

On 07/31/2013 08:17 PM, Olof Johansson wrote:
> Hi,
> On Wed, Jul 31, 2013 at 2:02 AM, Lars-Peter Clausen <lars at metafoo.de> wrote:
>> On 07/31/2013 10:52 AM, Dan Carpenter wrote:
>>> There is a typo here so we end up using the old freed pointer instead of
>>> the newly allocated one.  (If the "n" is zero then the code works,
>>> obviously).
>>> Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
>> Thanks.
>> Acked-by: Lars-Peter Clausen <lars at metafoo.de>
>> Olof, can you check whether this fixes the crash you see?
> Nope.
> There's also remaining issues with the code, that patch isn't enough.
> The structure that is krealloced() has a list_head in it, but the list
> isn't moved from the old head to the new one. There's no safe way to
> do that using krealloc, since the old list_head is gone by then, so
> it's probably easest to open-code with kzalloc/memcpy/kfree.

Hm, right I didn't think of that. Maybe it's better to just keep a the widget 
list in a separate pointer, so none of the other fields of the kcontrol_data 
struct are affected by the krealloc.

- Lars

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