FAILED: patch "[PATCH] ALSA: emux: Stop voices before freeing zones in all cases" failed to apply to 6.6-stable tree

[Sasha Levin <sashal@kernel.org>]

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 8a5d87c2ba30e8de31cfbe888fd4d95f43c63db9
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261107053715-failed-6.6-8a5d87c2ba30@kernel.org' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From 8a5d87c2ba30e8de31cfbe888fd4d95f43c63db9 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Tue, 20 Oct 2026 12:16:21 +0200
Subject: [PATCH] ALSA: emux: Stop voices before freeing zones in all cases

The emux voice caches the soundfont zone pointer in vp->zone, which
is referred to later, e.g. in snd_emux_send_effect().  For avoiding
dangling pointers, the soundfont code calls the sample_reset callback
to stop all voices before freeing zones.  However, in a few cases
(e.g. emu10k1's missing sample_reset or the call path via
remove_info()), the sample reset isn't called properly, leaving the
playing voices.

Fix it by always registering the sample_reset callback, falling back
to snd_emux_terminate_all() when the driver has no own ops, and by
calling sample_reset in remove_info() before freeing the zones.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20261020101624.205638-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/synth/emux/emux.c      | 10 +++++++---
 sound/synth/emux/soundfont.c |  9 +++++++++
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/sound/synth/emux/emux.c b/sound/synth/emux/emux.c
index 450147b1abed5..2a42d041e1da0 100644
--- a/sound/synth/emux/emux.c
+++ b/sound/synth/emux/emux.c
@@ -71,7 +71,12 @@ static int sf_sample_free(void *private_data, struct snd_sf_sample *sp,
 static void sf_sample_reset(void *private_data)
 {
 	struct snd_emux *emu = private_data;
-	emu->ops.sample_reset(emu);
+
+	/* stop all voices that might refer to zones and samples to be freed */
+	if (emu->ops.sample_reset)
+		emu->ops.sample_reset(emu);
+	else
+		snd_emux_terminate_all(emu);
 }
 
 int snd_emux_register(struct snd_emux *emu, struct snd_card *card, int index, char *name)
@@ -95,8 +100,7 @@ int snd_emux_register(struct snd_emux *emu, struct snd_card *card, int index, ch
 	sf_cb.private_data = emu;
 	sf_cb.sample_new = sf_sample_new;
 	sf_cb.sample_free = sf_sample_free;
-	if (emu->ops.sample_reset)
-		sf_cb.sample_reset = sf_sample_reset;
+	sf_cb.sample_reset = sf_sample_reset;
 	emu->sflist = snd_sf_new(&sf_cb, emu->memhdr);
 	if (emu->sflist == NULL)
 		return -ENOMEM;
diff --git a/sound/synth/emux/soundfont.c b/sound/synth/emux/soundfont.c
index 039357d96e07a..42d1f33fb2b50 100644
--- a/sound/synth/emux/soundfont.c
+++ b/sound/synth/emux/soundfont.c
@@ -443,6 +443,15 @@ remove_info(struct snd_sf_list *sflist, struct snd_soundfont *sf,
 	struct snd_sf_zone *prev, *next, *p;
 	int removed = 0;
 
+	/* stop voices before freeing the zones they might refer to */
+	for (p = sf->zones; p; p = p->next) {
+		if (!p->mapped && p->bank == bank && p->instr == instr) {
+			if (sflist->callback.sample_reset)
+				sflist->callback.sample_reset(sflist->callback.private_data);
+			break;
+		}
+	}
+
 	prev = NULL;
 	for (p = sf->zones; p; p = next) {
 		next = p->next;
-- 
2.53.0