On Wed, Oct 21, 2020 at 11:03:11PM +0800, Hui Wang wrote:
Looks like this will not bring problem on patch_sigmatel.c, NULL and valid kernel pointer are same for IS_ERR(), they will not make IS_ERR() come true.
Correct, but that is the problem. You can dereference a valid pointer but you can't dereference a NULL.
On 10/21/20 10:21 PM, Hui Wang wrote:
On 10/21/20 8:19 PM, Dan Carpenter wrote:
Hello Hui Wang,
The patch f4794c6064a8: "ALSA: hda - Don't register a cb func if it is registered already" from Sep 30, 2020, leads to the following static checker warning:
sound/pci/hda/patch_sigmatel.c:3075 stac92hd71bxx_fixup_hp_m4() warn: 'jack' can also be NULL
sound/pci/hda/patch_sigmatel.c 3069 /* Enable VREF power saving on GPIO1 detect */ 3070 snd_hda_codec_write_cache(codec, codec->core.afg, 0, 3071 AC_VERB_SET_GPIO_UNSOLICITED_RSP_MASK, 0x02); 3072 jack = snd_hda_jack_detect_enable_callback(codec, codec->core.afg, 3073 stac_vref_event);
Originally snd_hda_jack_detect_enable_callback() would not return NULL here.
3074 if (!IS_ERR(jack)) 3075 jack->private_data = 0x02;
So if "jack" is NULL then it will say it's not an error pointer so it will try to assign jack->private_data = 0x02; and oops.
regards, dan carpenter