commit 826af7fa62e347464b1b4e0ba2fe19a92438084f upstream.

The PCM trigger callback of aloop driver tries to check the PCM state
and stop the stream of the tied substream in the corresponding cable.
Since both check and stop operations are performed outside the cable
lock, this may result in UAF when a program attempts to trigger
frequently while opening/closing the tied stream, as spotted by
fuzzers.

For addressing the UAF, this patch changes two things:
- It covers the most of code in loopback_check_format() with
  cable->lock spinlock, and add the proper NULL checks.  This avoids
  already some racy accesses.
- In addition, now we try to check the state of the capture PCM stream
  that may be stopped in this function, which was the major pain point
  leading to UAF.

Reported-by: syzbot+5f8f3acdee1ec7a7ef7b@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/69783ba1.050a0220.c9109.0011.GAE@google.com
Cc: <stable@vger.kernel.org>
Link: https://patch.msgid.link/20260203141003.116584-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit 84973249011fda3ff292f83439a062fec81ef982 ]

If multiple instances of this driver are instantiated and try to send
concurrently then the single static buffer snd_serial_generic_tx_work()
will cause corruption in the data output.

Move the buffer into the per-instance driver data to avoid this.

Signed-off-by: John Keeping <jkeeping@inmusicbrands.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Allow using global timers as a timer source when card id is equal to -1
in the timer_source parameter.

Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20240813120701.171743-2-ivan.orlov0322@gmail.com

Use the standard print API with dev_*() instead of the old house-baked
one.  It gives better information and allows dynamically control of
debug prints.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20240807133452.9424-15-tiwai@suse.de

Use pr_*() macro instead of open-coded printk() just for code
simplification.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20240807133452.9424-14-tiwai@suse.de

Use pr_err() instead of open-coded printk() just for code
simplification.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20240807133452.9424-13-tiwai@suse.de

Use the standard print API with dev_*() instead of the old house-baked
one.  It gives better information and allows dynamically control of
debug prints.

The commented old debug prints are dropped, too.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20240807133452.9424-12-tiwai@suse.de

The vx_core.dev field has never been set but referred incorrectly at
firmware loading.  Pass the proper device pointer from card->dev at
request_firmware(), and drop the unused dev field from vx_core, too.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20240807133452.9424-11-tiwai@suse.de

Use the standard print API with dev_*() instead of the old house-baked
one.  It gives better information and allows dynamically control of
debug prints.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20240807133452.9424-10-tiwai@suse.de

Use the standard print API with dev_*() instead of the old house-baked
one.  It gives better information and allows dynamically control of
debug prints.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20240807133452.9424-9-tiwai@suse.de