[PATCH 3.2 030/221] ALSA: off by one bug in snd_riptide_joystick_probe()

Ben Hutchings
2015-05-05T01:59:18Z

From: Dan Carpenter <dan.carpenter@oracle.com>

commit e4940626defdf6c92da1052ad3f12741c1a28c90 upstream.

The problem here is that we check:

if (dev >= SNDRV_CARDS)

Then we increment "dev".

if (!joystick_port[dev++])

Then we use it as an offset into a array with SNDRV_CARDS elements.

if (!request_region(joystick_port[dev], 8, "Riptide gameport")) {

This has 3 effects:
1) If you use the module option to specify the joystick port then it has
to be shifted one space over.
2) The wrong error message will be printed on failure if you have over
32 cards.
3) Static checkers will correctly complain that are off by one.

Fixes: db1005ec6ff8 ('ALSA: riptide - Fix joystick resource handling')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
sound/pci/riptide/riptide.c | 27 +++++++++++++++++++--------
1 file changed, 19 insertions(+), 8 deletions(-)

--- a/sound/pci/riptide/riptide.c
+++ b/sound/pci/riptide/riptide.c
@@ -2026,32 +2026,43 @@ snd_riptide_joystick_probe(struct pci_de
{
static int dev;
struct gameport *gameport;
+ int ret;

if (dev >= SNDRV_CARDS)
return -ENODEV;
+
if (!enable[dev]) {
- dev++;
- return -ENOENT;
+ ret = -ENOENT;
+ goto inc_dev;
}

- if (!joystick_port[dev++])
- return 0;
+ if (!joystick_port[dev]) {
+ ret = 0;
+ goto inc_dev;
+ }

gameport = gameport_allocate_port();
- if (!gameport)
- return -ENOMEM;
+ if (!gameport) {
+ ret = -ENOMEM;
+ goto inc_dev;
+ }
if (!request_region(joystick_port[dev], 8, "Riptide gameport")) {
snd_printk(KERN_WARNING
"Riptide: cannot grab gameport 0x%x\n",
joystick_port[dev]);
gameport_free_port(gameport);
- return -EBUSY;
+ ret = -EBUSY;
+ goto inc_dev;
}

gameport->io = joystick_port[dev];
gameport_register_port(gameport);
pci_set_drvdata(pci, gameport);
- return 0;
+
+ ret = 0;
+inc_dev:
+ dev++;
+ return ret;
}

static void __devexit snd_riptide_joystick_remove(struct pci_dev *pci)