When snd_hdac_refresh_widget_sysfs() is called before the first hda_widget_sysfs_init(), the next call overrides and eventually fails. This results in unexpected Oops, something like: BUG: unable to handle kernel NULL pointer dereference at 00000000000000c8 IP: [<ffffffff8180e2a3>] hdmi_chmap_ctl_info+0x23/0x40

The fix is to add a check of the existing sysfs tree. Also, for more safety, this patch adds the checks of device_is_registered() in snd-hdac_refresh_wdiget_sysfs(), too.

Fixes: fa4f18b4f402 ('ALSA: hda - Refresh widgets sysfs at probing Haswell+ HDMI codecs') Bugizlla: https://bugzilla.kernel.org/show_bug.cgi?id=103431 Reported-by: Andreas Reis andreas.reis@gmail.com Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/hda/hdac_device.c | 14 ++++++++------ sound/hda/hdac_sysfs.c | 3 +++ 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/sound/hda/hdac_device.c b/sound/hda/hdac_device.c index aa6d6cec2380..db96042a497f 100644 --- a/sound/hda/hdac_device.c +++ b/sound/hda/hdac_device.c @@ -384,18 +384,20 @@ int snd_hdac_refresh_widget_sysfs(struct hdac_device *codec) { int ret;

- hda_widget_sysfs_exit(codec); + if (device_is_registered(&codec->dev)) + hda_widget_sysfs_exit(codec); ret = snd_hdac_refresh_widgets(codec); if (ret) { dev_err(&codec->dev, "failed to refresh widget: %d\n", ret); return ret; } - ret = hda_widget_sysfs_init(codec); - if (ret) { - dev_err(&codec->dev, "failed to init sysfs: %d\n", ret); - return ret; + if (device_is_registered(&codec->dev)) { + ret = hda_widget_sysfs_init(codec); + if (ret) { + dev_err(&codec->dev, "failed to init sysfs: %d\n", ret); + return ret; + } } - return ret; } EXPORT_SYMBOL_GPL(snd_hdac_refresh_widget_sysfs); diff --git a/sound/hda/hdac_sysfs.c b/sound/hda/hdac_sysfs.c index 089b35f6f108..c71142dea98a 100644 --- a/sound/hda/hdac_sysfs.c +++ b/sound/hda/hdac_sysfs.c @@ -390,6 +390,9 @@ int hda_widget_sysfs_init(struct hdac_device *codec) { int err;

+ if (codec->widgets) + return 0; /* already created */ + err = widget_tree_create(codec); if (err < 0) { widget_tree_free(codec);