Fix a use-after-free in snd_soc_dapm_stream_event() triggered when a
sound card is unbound while a PCM close delayed work is pending.

As Mark pointed out in v1 review, flush_delayed_work() does handle
pending timers correctly. The actual issue appears to be new work
getting scheduled after the flush: snd_card_disconnect_sync() inside
soc_cleanup_card_resources() can trigger PCM closes which call
snd_soc_dapm_stream_stop(), scheduling new delayed work after the
flush in snd_soc_unbind_card() has already completed. If the timer
fires after soc_remove_link_components() frees the DAPM widgets,
the work accesses freed memory.

v1 -> v2:
- Split into two patches as requested
- Dropped cancel_delayed_work_sync() approach, kept flush as suggested
- Added a flush in soc_cleanup_card_resources() after disconnect_sync
  (so no new work can be scheduled) and before DAIs/widgets are freed

matteo.cotifava (2):
  ASoC: soc-core: drop delayed_work_pending() check before flush
  ASoC: soc-core: flush delayed work before removing DAIs and widgets

 sound/soc/soc-core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

-- 
2.39.5

On Mon, 09 Mar 2026 22:54:10 +0100, matteo.cotifava wrote:
> Fix a use-after-free in snd_soc_dapm_stream_event() triggered when a
> sound card is unbound while a PCM close delayed work is pending.
> 
> As Mark pointed out in v1 review, flush_delayed_work() does handle
> pending timers correctly. The actual issue appears to be new work
> getting scheduled after the flush: snd_card_disconnect_sync() inside
> soc_cleanup_card_resources() can trigger PCM closes which call
> snd_soc_dapm_stream_stop(), scheduling new delayed work after the
> flush in snd_soc_unbind_card() has already completed. If the timer
> fires after soc_remove_link_components() frees the DAPM widgets,
> the work accesses freed memory.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/2] ASoC: soc-core: drop delayed_work_pending() check before flush
      commit: 3c99c9f0ed60582c1c9852b685d78d5d3a50de63
[2/2] ASoC: soc-core: flush delayed work before removing DAIs and widgets
      commit: 95bc5c225513fc3c4ce169563fb5e3929fbb938b

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

On Mon, Mar 09, 2026 at 10:54:10PM +0100, matteo.cotifava wrote:
> Fix a use-after-free in snd_soc_dapm_stream_event() triggered when a
> sound card is unbound while a PCM close delayed work is pending.

Please don't send new patches in reply to old patches or serieses, this
makes it harder for both people and tools to understand what is going
on - it can bury things in mailboxes and make it difficult to keep track
of what current patches are, both for the new patches and the old ones.