[PATCH AUTOSEL 5.15 4/8] sound/virtio: Fix cancel_sync warnings on uninitialized work_structs

[PATCH AUTOSEL 5.15 4/8] sound/virtio: Fix cancel_sync warnings on uninitialized work_structs

[Sasha Levin]

From: John Stultz <jstultz@google.com>

[ Upstream commit 3c7df2e27346eb40a0e86230db1ccab195c97cfe ]

Betty reported hitting the following warning:

[    8.709131][  T221] WARNING: CPU: 2 PID: 221 at kernel/workqueue.c:4182
...
[    8.713282][  T221] Call trace:
[    8.713365][  T221]  __flush_work+0x8d0/0x914
[    8.713468][  T221]  __cancel_work_sync+0xac/0xfc
[    8.713570][  T221]  cancel_work_sync+0x24/0x34
[    8.713667][  T221]  virtsnd_remove+0xa8/0xf8 [virtio_snd ab15f34d0dd772f6d11327e08a81d46dc9c36276]
[    8.713868][  T221]  virtsnd_probe+0x48c/0x664 [virtio_snd ab15f34d0dd772f6d11327e08a81d46dc9c36276]
[    8.714035][  T221]  virtio_dev_probe+0x28c/0x390
[    8.714139][  T221]  really_probe+0x1bc/0x4c8
...

It seems we're hitting the error path in virtsnd_probe(), which
triggers a virtsnd_remove() which iterates over the substreams
calling cancel_work_sync() on the elapsed_period work_struct.

Looking at the code, from earlier in:
virtsnd_probe()->virtsnd_build_devs()->virtsnd_pcm_parse_cfg()

We set snd->nsubstreams, allocate the snd->substreams, and if
we then hit an error on the info allocation or something in
virtsnd_ctl_query_info() fails, we will exit without having
initialized the elapsed_period work_struct.

When that error path unwinds we then call virtsnd_remove()
which as long as the substreams array is allocated, will iterate
through calling cancel_work_sync() on the uninitialized work
struct hitting this warning.

Takashi Iwai suggested this fix, which initializes the substreams
structure right after allocation, so that if we hit the error
paths we avoid trying to cleanup uninitialized data.

Note: I have not yet managed to reproduce the issue myself, so
this patch has had limited testing.

Feedback or thoughts would be appreciated!

Cc: Anton Yakovlev <anton.yakovlev@opensynergy.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: virtualization@lists.linux.dev
Cc: linux-sound@vger.kernel.org
Cc: kernel-team@android.com
Reported-by: Betty Zhou <bettyzhou@google.com>
Suggested-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: John Stultz <jstultz@google.com>
Message-Id: <20250116194114.3375616-1-jstultz@google.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 sound/virtio/virtio_pcm.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/sound/virtio/virtio_pcm.c b/sound/virtio/virtio_pcm.c
index c10d91fff2fb0..1ddec1f4f05d5 100644
--- a/sound/virtio/virtio_pcm.c
+++ b/sound/virtio/virtio_pcm.c
@@ -337,6 +337,21 @@ int virtsnd_pcm_parse_cfg(struct virtio_snd *snd)
 	if (!snd->substreams)
 		return -ENOMEM;
 
+	/*
+	 * Initialize critical substream fields early in case we hit an
+	 * error path and end up trying to clean up uninitialized structures
+	 * elsewhere.
+	 */
+	for (i = 0; i < snd->nsubstreams; ++i) {
+		struct virtio_pcm_substream *vss = &snd->substreams[i];
+
+		vss->snd = snd;
+		vss->sid = i;
+		INIT_WORK(&vss->elapsed_period, virtsnd_pcm_period_elapsed);
+		init_waitqueue_head(&vss->msg_empty);
+		spin_lock_init(&vss->lock);
+	}
+
 	info = kcalloc(snd->nsubstreams, sizeof(*info), GFP_KERNEL);
 	if (!info)
 		return -ENOMEM;
@@ -350,12 +365,6 @@ int virtsnd_pcm_parse_cfg(struct virtio_snd *snd)
 		struct virtio_pcm_substream *vss = &snd->substreams[i];
 		struct virtio_pcm *vpcm;
 
-		vss->snd = snd;
-		vss->sid = i;
-		INIT_WORK(&vss->elapsed_period, virtsnd_pcm_period_elapsed);
-		init_waitqueue_head(&vss->msg_empty);
-		spin_lock_init(&vss->lock);
-
 		rc = virtsnd_pcm_build_hw(vss, &info[i]);
 		if (rc)
 			goto on_exit;
-- 
2.39.5

[PATCH AUTOSEL 5.15 8/8] objtool, ASoC: codecs: wcd934x: Remove potential undefined behavior in wcd934x_slim_irq_handler()

[Sasha Levin]

From: Josh Poimboeuf <jpoimboe@kernel.org>

[ Upstream commit 060aed9c0093b341480770457093449771cf1496 ]

If 'port_id' is negative, the shift counts in wcd934x_slim_irq_handler()
also become negative, resulting in undefined behavior due to shift out
of bounds.

If I'm reading the code correctly, that appears to be not possible, but
with KCOV enabled, Clang's range analysis isn't always able to determine
that and generates undefined behavior.

As a result the code generation isn't optimal, and undefined behavior
should be avoided regardless.  Improve code generation and remove the
undefined behavior by converting the signed variables to unsigned.

Fixes the following warning with UBSAN:

  sound/soc/codecs/snd-soc-wcd934x.o: warning: objtool: .text.wcd934x_slim_irq_handler: unexpected end of section

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Mark Brown <broonie@kernel.org>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/7e863839ec7301bf9c0f429a03873d44e484c31c.1742852847.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/oe-kbuild-all/202503180044.oH9gyPeg-lkp@intel.com/
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 sound/soc/codecs/wcd934x.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/soc/codecs/wcd934x.c b/sound/soc/codecs/wcd934x.c
index 94ffd2ba29aef..765ac2a3e9638 100644
--- a/sound/soc/codecs/wcd934x.c
+++ b/sound/soc/codecs/wcd934x.c
@@ -2281,7 +2281,7 @@ static irqreturn_t wcd934x_slim_irq_handler(int irq, void *data)
 {
 	struct wcd934x_codec *wcd = data;
 	unsigned long status = 0;
-	int i, j, port_id;
+	unsigned int i, j, port_id;
 	unsigned int val, int_val = 0;
 	irqreturn_t ret = IRQ_NONE;
 	bool tx;
-- 
2.39.5