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ALSA: cs4236: fix an incorrect NULL check on list iterator 

commit 0112f822f8 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: c2b73d1458 ("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>
This commit is contained in:
Xiaomeng Tong 2022-03-27 14:08:22 +08:00 committed by Greg Kroah-Hartman
parent edefc4b2a8
commit a55e2d7423
1 changed files with 5 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
sound/isa/cs423x/cs4236.c
View File

@ -544,7 +544,7 @@ static int snd_cs423x_pnpbios_detect(struct pnp_dev *pdev,
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))
@ -560,9 +560,11 @@ static int snd_cs423x_pnpbios_detect(struct pnp_dev *pdev,
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)