Re: [PATCH] ALSA: pcmtest: fix reference leak on failed device registration

[Jiri Slaby]

On 17. 04. 26, 12:52, Takashi Iwai wrote:
> On Fri, 17 Apr 2026 09:57:20 +0200,
> Takashi Iwai wrote:
> > On Wed, 15 Apr 2026 21:31:38 +0200,
> > Guangshuo Li wrote:
> > > When platform_device_register() fails in mod_init(), the embedded struct
> > > device in pcmtst_pdev has already been initialized by
> > > device_initialize(), but the failure path returns the error without
> > > dropping the device reference for the current platform device:
> > >
> > >    mod_init()
> > >      -> platform_device_register(&pcmtst_pdev)
> > >         -> device_initialize(&pcmtst_pdev.dev)
> > >         -> setup_pdev_dma_masks(&pcmtst_pdev)
> > >         -> platform_device_add(&pcmtst_pdev)
> > >
> > > This leads to a reference leak when platform_device_register() fails.
> > > Fix this by calling platform_device_put() before returning the error.
> > >
> > > The issue was identified by a static analysis tool I developed and
> > > confirmed by manual review.
> > >
> > > Fixes: 315a3d57c64c5 ("ALSA: Implement the new Virtual PCM Test Driver")
> > > Cc: stable@xxxxxxxxxxxxxxx
> > > Signed-off-by: Guangshuo Li <lgs201920130244@xxxxxxxxx>
> >
> > Thanks, applied now.
>
> ... and now I looked through the whole tree, and noticed that the
> majority of callers of platform_device_register() don't care the error
> cases without calling platform_device_put().  There are over a hundred
> callers of platform_device_register() while only 5 or so are doing the
> proper cleanup at the error.

Moreover, unless the static pcmtst_pdev has ->type->release or ->release 
set, the patch triggers a warning upon put().

> Judging from the numbers above, it might be better to change the
> behavior of platform_device_register() itself to call *_put() at the
> error case internally.

Yes, that's what should be done instead.

thanks,
--
js
suse labs