Fallout from commit 70fdb77 "audio/avrcp: Fix not always requesting capabilities"

Fallout from commit 70fdb77 "audio/avrcp: Fix not always requesting capabilities"

[Ivan Shapovalov]

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Hello,

The commit 70fdb7 "audio/avrcp: Fix not always requesting capabilities"
introduced a series of bugs where the code thinks that session-
>controller->player cannot be NULL, but in fact it can be so. The first
one was fixed in 177d27 "audio/avrcp: Fix crash when connecting to controllers", but there remain multiple code pathes via avrcp_register_notification() -> callback -> avrcp_handle_event() -> avrcp_{status,track,playback_pos,settings,uids}_changed() where session->controller->player may be dereferenced.

I'm unsure how to fix that properly (either not register notifications,
or ignore specific callbacks if s->c->player is NULL), so I'm just
reporting this.

Ref.: https://bugs.archlinux.org/task/48644

-- 
Ivan Shapovalov / intelfx /


Please Cc: me on replies as I'm not subscribed to the list.

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Re: Fallout from commit 70fdb77 "audio/avrcp: Fix not always requesting capabilities"

[Luiz Augusto von Dentz]

Hi Ivan,

On Thu, Mar 31, 2016 at 8:00 PM, Ivan Shapovalov <intelfx@intelfx.name> wrote:
> Hello,
>
> The commit 70fdb7 "audio/avrcp: Fix not always requesting capabilities"
> introduced a series of bugs where the code thinks that session-
>>controller->player cannot be NULL, but in fact it can be so. The first
> one was fixed in 177d27 "audio/avrcp: Fix crash when connecting to controllers", but there remain multiple code pathes via avrcp_register_notification() -> callback -> avrcp_handle_event() -> avrcp_{status,track,playback_pos,settings,uids}_changed() where session->controller->player may be dereferenced.
>
> I'm unsure how to fix that properly (either not register notifications,
> or ignore specific callbacks if s->c->player is NULL), so I'm just
> reporting this.
>
> Ref.: https://bugs.archlinux.org/task/48644

Ive just sent a patch to prevent the above to happen, it is very
uncommon that those event would be supported for a controller that
does not have player capabilities but indeed it could cause crashes.

-- 
Luiz Augusto von Dentz