On Wed, 22 Feb 2017 02:42:39 +0100, Takashi Sakamoto wrote:
On Feb 22 2017 07:59, Takashi Sakamoto wrote:
On Feb 22 2017 07:45, Takashi Sakamoto wrote:
On Fe 21 2017 11:32, Takashi Sakamoto wrote:
But it's wrong. The allocated memory objects are used for private data for each control element set. I didn't care of it...
Here, what I should fix is just for error path. I'll post revised version of this patch this night.
I realize that this is not concern because the code includes assignment deallocate function to each control element set. Thus, in error path, the allocated private data is going to free in below callgrach.
(sound/usb/mixer_us16x08.c) add_new_ctl(elem) kctl->private_free = freeer; (sound/usb/mixer.c) ->snd_usb_mixer_add_control(kctl) (sound/core/control.c) ->snd_ctl_add(kctl) ->snd_ctl_free_one(kctl) (in error path) ->kcontrol->private_free(kctl); (sound/usb/mixer_us16x08.c) = freeer()
Oops. On the other hand, the private data for unregistered control element set is not deallocated automatically in error path of the other control element set. It should be fixed...
Mmm. There might be an issue of double free corruption, I think.
(sound/core/control.c) ->snd_ctl_add(kctl) (in error path) ->snd_ctl_free_one(kctl) ->kcontrol->private_free(kctl); (sound/usb/mixer_us16x08.c) = freeer()This 'freeer()' is set in beginning of the graph.
(sound/usb/mixer_us16x08.c) add_new_ctl(elem) kctl->private_free = freeer;
The memory objects are not allocated for each of the control element set. On the other hand, the calls of the 'freeer()' are corresponding to each control element set. When the ratio between .private_data/.private_free and control element set is 1:N, .private_free can cause double free corruption at freeing control character device in kernel side.
In current code, there're two cases; NULL or 'snd_usb_mixer_elem_free()' are assigned as the 'freeer()'. But this is not enough. Actually, the allocated memory object for the 'comp_store' variable is going to be deallocated by two control element sets; for 'channel_controls[0]' and 'channel_controls[0]' the allocated memory object for the 'eq_sotre' variable is going to be deallocated for several control element sets; the 'eq_controls[0, 1, 3, 6, 9]'.
As long as I understand, current code has the above issue and can bring kernel corruption. If I missing something, please inform it to me.
Yeah, there are quite a few memory leaks and double frees. The patch below is a bit of drastic surgery.
Takashi
-- 8< -- From: Takashi Iwai tiwai@suse.de Subject: [PATCH] ALSA: usb-audio: Fix memory leak and corruption in mixer_us16x08.c
There are a few places leaking memory and doing double-free in mixer_us16x08.c.
The driver allocates a usb_mixer_elem_info object at each add_new_ctl() call. This has to be freed via kctl->private_free, but currently this is done properly only for some controls.
Also, the driver allocates three external objects (comp_store, eq_store, meter_store), and these are referred in elem->private_data (it's not kctl->private_data). And these have to be released, but there are none doing it. Moreover, these extra objects have to be released only once. Thus the release should be done only by the first kctl element that refers to it.
For fixing these, we call either snd_usb_mixer_elem_free() (only for kctl->private_data) or elem_private_free() (for both kctl->private_data and elem->private_data) via kctl->private_free appropriately.
Last but not least, snd_us16x08_controls_create() may return in the middle without releasing the allocated *_store objects. returns in the middle due to an error. For fixing this, we shuffle the allocation code so that it's called just before its reference.
Fixes: d2bb390a2081 ("ALSA: usb-audio: Tascam US-16x08 DSP mixer quirk") Reported-by: Takashi Sakamoto o-takashi@sakamocchi.jp Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/usb/mixer_us16x08.c | 92 ++++++++++++++++++++--------------------------- sound/usb/mixer_us16x08.h | 1 - 2 files changed, 39 insertions(+), 54 deletions(-)
diff --git a/sound/usb/mixer_us16x08.c b/sound/usb/mixer_us16x08.c index 73a0b9afdd70..f7289541fbce 100644 --- a/sound/usb/mixer_us16x08.c +++ b/sound/usb/mixer_us16x08.c @@ -1053,11 +1053,22 @@ static struct snd_us16x08_meter_store *snd_us16x08_create_meter_store(void)
}
+/* release elem->private_free as well; called only once for each *_store */ +static void elem_private_free(struct snd_kcontrol *kctl) +{ + struct usb_mixer_elem_info *elem = kctl->private_data; + + if (elem) + kfree(elem->private_data); + kfree(elem); + kctl->private_data = NULL; +} + static int add_new_ctl(struct usb_mixer_interface *mixer, const struct snd_kcontrol_new *ncontrol, int index, int val_type, int channels, const char *name, const void *opt, - void (*freeer)(struct snd_kcontrol *kctl), + bool do_private_free, struct usb_mixer_elem_info **elem_ret) { struct snd_kcontrol *kctl; @@ -1085,7 +1096,10 @@ static int add_new_ctl(struct usb_mixer_interface *mixer, return -ENOMEM; }
- kctl->private_free = freeer; + if (do_private_free) + kctl->private_free = elem_private_free; + else + kctl->private_free = snd_usb_mixer_elem_free;
strlcpy(kctl->id.name, name, sizeof(kctl->id.name));
@@ -1109,7 +1123,6 @@ static struct snd_us16x08_control_params eq_controls[] = { .type = USB_MIXER_BOOLEAN, .num_channels = 16, .name = "EQ Switch", - .freeer = snd_usb_mixer_elem_free }, { /* EQ low gain */ .kcontrol_new = &snd_us16x08_eq_gain_ctl, @@ -1117,7 +1130,6 @@ static struct snd_us16x08_control_params eq_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "EQ Low Volume", - .freeer = snd_usb_mixer_elem_free }, { /* EQ low freq */ .kcontrol_new = &snd_us16x08_eq_low_freq_ctl, @@ -1125,7 +1137,6 @@ static struct snd_us16x08_control_params eq_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "EQ Low Frequence", - .freeer = NULL }, { /* EQ mid low gain */ .kcontrol_new = &snd_us16x08_eq_gain_ctl, @@ -1133,7 +1144,6 @@ static struct snd_us16x08_control_params eq_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "EQ MidLow Volume", - .freeer = snd_usb_mixer_elem_free }, { /* EQ mid low freq */ .kcontrol_new = &snd_us16x08_eq_mid_freq_ctl, @@ -1141,7 +1151,6 @@ static struct snd_us16x08_control_params eq_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "EQ MidLow Frequence", - .freeer = NULL }, { /* EQ mid low Q */ .kcontrol_new = &snd_us16x08_eq_mid_width_ctl, @@ -1149,7 +1158,6 @@ static struct snd_us16x08_control_params eq_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "EQ MidQLow Q", - .freeer = NULL }, { /* EQ mid high gain */ .kcontrol_new = &snd_us16x08_eq_gain_ctl, @@ -1157,7 +1165,6 @@ static struct snd_us16x08_control_params eq_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "EQ MidHigh Volume", - .freeer = snd_usb_mixer_elem_free }, { /* EQ mid high freq */ .kcontrol_new = &snd_us16x08_eq_mid_freq_ctl, @@ -1165,7 +1172,6 @@ static struct snd_us16x08_control_params eq_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "EQ MidHigh Frequence", - .freeer = NULL }, { /* EQ mid high Q */ .kcontrol_new = &snd_us16x08_eq_mid_width_ctl, @@ -1173,7 +1179,6 @@ static struct snd_us16x08_control_params eq_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "EQ MidHigh Q", - .freeer = NULL }, { /* EQ high gain */ .kcontrol_new = &snd_us16x08_eq_gain_ctl, @@ -1181,7 +1186,6 @@ static struct snd_us16x08_control_params eq_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "EQ High Volume", - .freeer = snd_usb_mixer_elem_free }, { /* EQ low freq */ .kcontrol_new = &snd_us16x08_eq_high_freq_ctl, @@ -1189,7 +1193,6 @@ static struct snd_us16x08_control_params eq_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "EQ High Frequence", - .freeer = NULL }, };
@@ -1201,7 +1204,6 @@ static struct snd_us16x08_control_params comp_controls[] = { .type = USB_MIXER_BOOLEAN, .num_channels = 16, .name = "Compressor Switch", - .freeer = snd_usb_mixer_elem_free }, { /* Comp threshold */ .kcontrol_new = &snd_us16x08_comp_threshold_ctl, @@ -1209,7 +1211,6 @@ static struct snd_us16x08_control_params comp_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "Compressor Threshold Volume", - .freeer = NULL }, { /* Comp ratio */ .kcontrol_new = &snd_us16x08_comp_ratio_ctl, @@ -1217,7 +1218,6 @@ static struct snd_us16x08_control_params comp_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "Compressor Ratio", - .freeer = NULL }, { /* Comp attack */ .kcontrol_new = &snd_us16x08_comp_attack_ctl, @@ -1225,7 +1225,6 @@ static struct snd_us16x08_control_params comp_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "Compressor Attack", - .freeer = NULL }, { /* Comp release */ .kcontrol_new = &snd_us16x08_comp_release_ctl, @@ -1233,7 +1232,6 @@ static struct snd_us16x08_control_params comp_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "Compressor Release", - .freeer = NULL }, { /* Comp gain */ .kcontrol_new = &snd_us16x08_comp_gain_ctl, @@ -1241,7 +1239,6 @@ static struct snd_us16x08_control_params comp_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "Compressor Volume", - .freeer = NULL }, };
@@ -1253,7 +1250,6 @@ static struct snd_us16x08_control_params channel_controls[] = { .type = USB_MIXER_BOOLEAN, .num_channels = 16, .name = "Phase Switch", - .freeer = snd_usb_mixer_elem_free, .default_val = 0 }, { /* Fader */ @@ -1262,7 +1258,6 @@ static struct snd_us16x08_control_params channel_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "Line Volume", - .freeer = NULL, .default_val = 127 }, { /* Mute */ @@ -1271,7 +1266,6 @@ static struct snd_us16x08_control_params channel_controls[] = { .type = USB_MIXER_BOOLEAN, .num_channels = 16, .name = "Mute Switch", - .freeer = NULL, .default_val = 0 }, { /* Pan */ @@ -1280,7 +1274,6 @@ static struct snd_us16x08_control_params channel_controls[] = { .type = USB_MIXER_U16, .num_channels = 16, .name = "Pan Left-Right Volume", - .freeer = NULL, .default_val = 127 }, }; @@ -1293,7 +1286,6 @@ static struct snd_us16x08_control_params master_controls[] = { .type = USB_MIXER_U8, .num_channels = 16, .name = "Master Volume", - .freeer = NULL, .default_val = 127 }, { /* Bypass */ @@ -1302,7 +1294,6 @@ static struct snd_us16x08_control_params master_controls[] = { .type = USB_MIXER_BOOLEAN, .num_channels = 16, .name = "DSP Bypass Switch", - .freeer = NULL, .default_val = 0 }, { /* Buss out */ @@ -1311,7 +1302,6 @@ static struct snd_us16x08_control_params master_controls[] = { .type = USB_MIXER_BOOLEAN, .num_channels = 16, .name = "Buss Out Switch", - .freeer = NULL, .default_val = 0 }, { /* Master mute */ @@ -1320,7 +1310,6 @@ static struct snd_us16x08_control_params master_controls[] = { .type = USB_MIXER_BOOLEAN, .num_channels = 16, .name = "Master Mute Switch", - .freeer = NULL, .default_val = 0 },
@@ -1338,30 +1327,10 @@ int snd_us16x08_controls_create(struct usb_mixer_interface *mixer) /* just check for non-MIDI interface */ if (mixer->hostif->desc.bInterfaceNumber == 3) {
- /* create compressor mixer elements */ - comp_store = snd_us16x08_create_comp_store(); - if (comp_store == NULL) - return -ENOMEM; - - /* create eq store */ - eq_store = snd_us16x08_create_eq_store(); - if (eq_store == NULL) { - kfree(comp_store); - return -ENOMEM; - } - - /* create meters store */ - meter_store = snd_us16x08_create_meter_store(); - if (meter_store == NULL) { - kfree(comp_store); - kfree(eq_store); - return -ENOMEM; - } - /* add routing control */ err = add_new_ctl(mixer, &snd_us16x08_route_ctl, SND_US16X08_ID_ROUTE, USB_MIXER_U8, 8, "Line Out Route", - NULL, NULL, &elem); + NULL, false, &elem); if (err < 0) { usb_audio_dbg(mixer->chip, "Failed to create route control, err:%d\n", @@ -1372,6 +1341,11 @@ int snd_us16x08_controls_create(struct usb_mixer_interface *mixer) elem->cache_val[i] = i < 2 ? i : i + 2; elem->cached = 0xff;
+ /* create compressor mixer elements */ + comp_store = snd_us16x08_create_comp_store(); + if (!comp_store) + return -ENOMEM; + /* add master controls */ for (i = 0; i < sizeof(master_controls) @@ -1385,7 +1359,8 @@ int snd_us16x08_controls_create(struct usb_mixer_interface *mixer) master_controls[i].num_channels, master_controls[i].name, comp_store, - master_controls[i].freeer, &elem); + i == 0, /* release comp_store only once */ + &elem); if (err < 0) return err; elem->cache_val[0] = master_controls[i].default_val; @@ -1405,7 +1380,7 @@ int snd_us16x08_controls_create(struct usb_mixer_interface *mixer) channel_controls[i].num_channels, channel_controls[i].name, comp_store, - channel_controls[i].freeer, &elem); + false, &elem); if (err < 0) return err; for (j = 0; j < SND_US16X08_MAX_CHANNELS; j++) { @@ -1415,6 +1390,11 @@ int snd_us16x08_controls_create(struct usb_mixer_interface *mixer) elem->cached = 0xffff; }
+ /* create eq store */ + eq_store = snd_us16x08_create_eq_store(); + if (!eq_store) + return -ENOMEM; + /* add EQ controls */ for (i = 0; i < sizeof(eq_controls) / sizeof(control_params); i++) { @@ -1426,7 +1406,8 @@ int snd_us16x08_controls_create(struct usb_mixer_interface *mixer) eq_controls[i].num_channels, eq_controls[i].name, eq_store, - eq_controls[i].freeer, NULL); + i == 0, /* release eq_store only once */ + NULL); if (err < 0) return err; } @@ -1444,18 +1425,23 @@ int snd_us16x08_controls_create(struct usb_mixer_interface *mixer) comp_controls[i].num_channels, comp_controls[i].name, comp_store, - comp_controls[i].freeer, NULL); + false, NULL); if (err < 0) return err; }
+ /* create meters store */ + meter_store = snd_us16x08_create_meter_store(); + if (!meter_store) + return -ENOMEM; + /* meter function 'get' must access to compressor store * so place a reference here */ meter_store->comp_store = comp_store; err = add_new_ctl(mixer, &snd_us16x08_meter_ctl, SND_US16X08_ID_METER, USB_MIXER_U16, 0, "Level Meter", - (void *) meter_store, snd_usb_mixer_elem_free, NULL); + meter_store, true, NULL); if (err < 0) return err; } diff --git a/sound/usb/mixer_us16x08.h b/sound/usb/mixer_us16x08.h index 64f89b5eca2d..a6312fb0f962 100644 --- a/sound/usb/mixer_us16x08.h +++ b/sound/usb/mixer_us16x08.h @@ -112,7 +112,6 @@ struct snd_us16x08_control_params { int type; int num_channels; const char *name; - void (*freeer)(struct snd_kcontrol *kctl); int default_val; };