From 02442d5fe8ee365a084b055d4fa81a0c1abfc3fd Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Thu, 6 Aug 2026 12:04:31 +0200 Subject: [PATCH] ALSA: dummy: Check card index validity at probe snd_dummy_probe() blindly trusts that the given devptr->id value is within the proper card index range. It's OK for the devices the driver itself creates at the module probe time, but if the device is bound manually via sysfs interface, this could be -1 as "none", and this leads to OOB access for index[] and other parameters. Add a sanity check for the card index and warn/correct it if it's a value out of the range. Reported-by: syzbot+2fb5d1f7cc4c1f132bcc@syzkaller.appspotmail.com Closes: https://lore.kernel.org/6a73bd4d.01d0871a.3a0d52.0005.GAE@google.com Cc: Link: https://patch.msgid.link/20260806100433.1287393-1-tiwai@suse.de Signed-off-by: Takashi Iwai --- sound/drivers/dummy.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/sound/drivers/dummy.c b/sound/drivers/dummy.c index 8836799727ea..022247354732 100644 --- a/sound/drivers/dummy.c +++ b/sound/drivers/dummy.c @@ -1042,6 +1042,12 @@ static int snd_dummy_probe(struct platform_device *devptr) int idx, err; int dev = devptr->id; + if (dev < 0 || dev >= SNDRV_CARDS) { + dev_warn(&devptr->dev, + "Invalid card index %d, using default 0\n", dev); + dev = 0; + } + err = snd_devm_card_new(&devptr->dev, index[dev], id[dev], THIS_MODULE, sizeof(struct snd_dummy), &card); if (err < 0)