Messages in this thread Patch in this message | | | Date | Wed, 4 Oct 2006 22:22:19 +0200 (CEST) | From | Jiri Kosina <> | Subject | [PATCH] ALSA: fix kernel panic in initialization of mpu401 driver |
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I am getting kernel panic (NULL pointer dereference) on boot, with kernel compiled with CONFIG_SND_MPU401_UART=y, on machine which does not have this piece of hardware.
I have traced the problem down to sound/drivers/mpu401/mpu401.c:snd_mpu401_probe() returning EINVAL, when either port or IRQ parameters are not specified.
In such case, the drivers/base/bus.c:bus_attach_device() does not perform klist_add_tail() call, but rather sets dev->is_registered to 0. This flag is however not checked by the driver, so later on, when alsa_card_mpu401_init() is called and platform_device_register_simple() fails, the following callchain happens, causing NULL pointer dereference: alsa_card_mpu401_init() -> platform_device_unregister() -> platform_device_del() -> device_del() -> bus_remove_device() -> klist_del() -> BOOM (the entry was not added to klist in bus_attach_device()).
Proper solution is returning ENODEV from the ->probe() routine, which will be correctly handled then by the rest of the device-driver attaching subsystem (namely the retval check in bus_attach_device()). The following patch fixes the problem, please apply.
Patch against current Linus' git tree.
Signed-off-by: Jiri Kosina <jikos@jikos.cz>
--- a/sound/drivers/mpu401/mpu401.c +++ b/sound/drivers/mpu401/mpu401.c @@ -104,11 +104,11 @@ static int __devinit snd_mpu401_probe(st if (port[dev] == SNDRV_AUTO_PORT) { snd_printk(KERN_ERR "specify port\n"); - return -EINVAL; + return -ENODEV; } if (irq[dev] == SNDRV_AUTO_IRQ) { snd_printk(KERN_ERR "specify or disable IRQ\n"); - return -EINVAL; + return -ENODEV; } err = snd_mpu401_create(dev, &card); if (err < 0) -- Jiri Kosina - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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