[PATCH] staging: bcm2835-audio: Fix memory corruption
phil at raspberrypi.org
Thu Aug 10 03:52:42 PDT 2017
On 10/08/2017 11:21, Dan Carpenter wrote:
> The original patch did not go through the normal review process...
> On Tue, Aug 08, 2017 at 01:05:02PM +0100, Phil Elwell wrote:
>> I'm all for fixing memory leaks, but freeing a block while it is still
>> being used is a recipe for hard-to-debug kernel exceptions.
> This bug completely breaks the driver doesn't it? It's not very subtle
> so it should be easy to diagnose with git bisect.
It's more subtle than that - the failure isn't consistent, sometimes crashing
and sometimes not depending on how and when memory is reused.
>> 1) There is already a vchi method for freeing the instance, so use it.
>> 2) Only call it on error, and then only before initted is false.
>> Signed-off-by: Phil Elwell <phil at raspberrypi.org>
>> Fixes: 0adbfd4694c2 ("staging: bcm2835-audio: fix memory leak in bcm2835_audio_open_connection()")
>> drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>> diff --git a/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c b/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c
>> index 5f3d8f2..89f96f3 100644
>> --- a/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c
>> +++ b/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c
>> @@ -409,6 +409,7 @@ static int bcm2835_audio_open_connection(struct bcm2835_alsa_stream *alsa_stream
>> LOG_ERR("%s: failed to connect VCHI instance (ret=%d)\n",
>> __func__, ret);
>> + vchi_disconnect(vchi_instance);
> This is ugly because why are we calling disconnect() if connect() fails?
> These functions should be symetric so disconnect only disconnects and
> we call a different function to undo vchi_initialise().
Agreed - I'm not going to change the API, but I can add a comment.
>> ret = -EIO;
>> goto err_free_mem;
> This label name is out of date. There is a later error path where
> vc_vchi_audio_init() fails and we leak on that path.
Also agreed. I'll rework it.
> Also why is
> vchi_instance a static variable? Arglebargleblargleblah...
You may well think that. I couldn't possibly comment.
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