[PATCH 1/2] ALSA: vmaster: Propagate slave error

[PATCH 1/2] ALSA: vmaster: Propagate slave error

[Takashi Iwai]

In slave_update() of vmaster code ignores the error from the slave
get() callback and copies the values.  It's not only about the missing
error code but also that this may potentially lead to a leak of
uninitialized variables when the slave get() don't clear them.

This patch fixes slave_update() not to copy the potentially
uninitialized values when an error is returned from the slave get()
callback, and to propagate the error value properly.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/core/vmaster.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sound/core/vmaster.c b/sound/core/vmaster.c
index 8632301489fa..b67de2bb06a2 100644
--- a/sound/core/vmaster.c
+++ b/sound/core/vmaster.c
@@ -68,10 +68,13 @@ static int slave_update(struct link_slave *slave)
 		return -ENOMEM;
 	uctl->id = slave->slave.id;
 	err = slave->slave.get(&slave->slave, uctl);
+	if (err < 0)
+		goto error;
 	for (ch = 0; ch < slave->info.count; ch++)
 		slave->vals[ch] = uctl->value.integer.value[ch];
+ error:
 	kfree(uctl);
-	return 0;
+	return err < 0 ? err : 0;
 }
 
 /* get the slave ctl info and save the initial values */
-- 
2.16.2

[PATCH 2/2] ALSA: vmaster: Zero-clear ctl before calling slave get

[Takashi Iwai]

Use kzalloc() instead of kmalloc() so that we don't need to rely fully
on the slave get() callback to clear the control value that might be
copied to user-space.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/core/vmaster.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/core/vmaster.c b/sound/core/vmaster.c
index b67de2bb06a2..9e96186742d0 100644
--- a/sound/core/vmaster.c
+++ b/sound/core/vmaster.c
@@ -63,7 +63,7 @@ static int slave_update(struct link_slave *slave)
 	struct snd_ctl_elem_value *uctl;
 	int err, ch;
 
-	uctl = kmalloc(sizeof(*uctl), GFP_KERNEL);
+	uctl = kzalloc(sizeof(*uctl), GFP_KERNEL);
 	if (!uctl)
 		return -ENOMEM;
 	uctl->id = slave->slave.id;
-- 
2.16.2