From: Xiaomeng Tong xiam0nd.tong@gmail.com
commit 0112f822f8a6d8039c94e0bc9b264d7ffc5d4704 upstream.
The bug is here: err = snd_card_cs423x_pnp(dev, card->private_data, pdev, cdev);
The list iterator value 'cdev' will *always* be set and non-NULL by list_for_each_entry(), so it is incorrect to assume that the iterator value will be NULL if the list is empty or no element is found.
To fix the bug, use a new variable 'iter' as the list iterator, while use the original variable 'cdev' as a dedicated pointer to point to the found element. And snd_card_cs423x_pnp() itself has NULL check for cdev.
Cc: stable@vger.kernel.org Fixes: c2b73d1458014 ("ALSA: cs4236: cs4232 and cs4236 driver merge to solve PnP BIOS detection") Signed-off-by: Xiaomeng Tong xiam0nd.tong@gmail.com Link: https://lore.kernel.org/r/20220327060822.4735-1-xiam0nd.tong@gmail.com Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- sound/isa/cs423x/cs4236.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
--- a/sound/isa/cs423x/cs4236.c +++ b/sound/isa/cs423x/cs4236.c @@ -494,7 +494,7 @@ static int snd_cs423x_pnpbios_detect(str static int dev; int err; struct snd_card *card; - struct pnp_dev *cdev; + struct pnp_dev *cdev, *iter; char cid[PNP_ID_LEN];
if (pnp_device_is_isapnp(pdev)) @@ -510,9 +510,11 @@ static int snd_cs423x_pnpbios_detect(str strcpy(cid, pdev->id[0].id); cid[5] = '1'; cdev = NULL; - list_for_each_entry(cdev, &(pdev->protocol->devices), protocol_list) { - if (!strcmp(cdev->id[0].id, cid)) + list_for_each_entry(iter, &(pdev->protocol->devices), protocol_list) { + if (!strcmp(iter->id[0].id, cid)) { + cdev = iter; break; + } } err = snd_cs423x_card_new(&pdev->dev, dev, &card); if (err < 0)