Messages in this thread | | | Subject | Re: [PATCH] staging: bcm2835-audio: Fix memory corruption | From | Phil Elwell <> | Date | Thu, 10 Aug 2017 11:52:42 +0100 |
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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@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 This label name is out of date.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.
Phil
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