Skip to content

Commit

Permalink
ALSA: hda/cs_dsp_ctl: Use private_free for control cleanup
Browse files Browse the repository at this point in the history
Use the control private_free callback to free the associated data
block. This ensures that the memory won't leak, whatever way the
control gets destroyed.

The original implementation didn't actually remove the ALSA
controls in hda_cs_dsp_control_remove(). It only freed the internal
tracking structure. This meant it was possible to remove/unload the
amp driver while leaving its ALSA controls still present in the
soundcard. Obviously attempting to access them could cause segfaults
or at least dereferencing stale pointers.

Signed-off-by: Richard Fitzgerald <[email protected]>
Fixes: 3233b97 ("ALSA: hda: hda_cs_dsp_ctl: Add Library to support CS_DSP ALSA controls")
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Takashi Iwai <[email protected]>
  • Loading branch information
rfvirgil authored and tiwai committed May 8, 2024
1 parent b7df4cc commit 172811e
Showing 1 changed file with 31 additions and 16 deletions.
47 changes: 31 additions & 16 deletions sound/pci/hda/hda_cs_dsp_ctl.c
Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@

#include <linux/module.h>
#include <sound/soc.h>
#include <linux/cleanup.h>
#include <linux/firmware/cirrus/cs_dsp.h>
#include <linux/firmware/cirrus/wmfw.h>
#include "hda_cs_dsp_ctl.h"
Expand Down Expand Up @@ -97,11 +98,23 @@ static unsigned int wmfw_convert_flags(unsigned int in)
return out;
}

static void hda_cs_dsp_add_kcontrol(struct hda_cs_dsp_coeff_ctl *ctl, const char *name)
static void hda_cs_dsp_free_kcontrol(struct snd_kcontrol *kctl)
{
struct hda_cs_dsp_coeff_ctl *ctl = (struct hda_cs_dsp_coeff_ctl *)snd_kcontrol_chip(kctl);
struct cs_dsp_coeff_ctl *cs_ctl = ctl->cs_ctl;

/* NULL priv to prevent a double-free in hda_cs_dsp_control_remove() */
cs_ctl->priv = NULL;
kfree(ctl);
}

static void hda_cs_dsp_add_kcontrol(struct cs_dsp_coeff_ctl *cs_ctl,
const struct hda_cs_dsp_ctl_info *info,
const char *name)
{
struct snd_kcontrol_new kcontrol = {0};
struct snd_kcontrol *kctl;
struct hda_cs_dsp_coeff_ctl *ctl __free(kfree) = NULL;
int ret = 0;

if (cs_ctl->len > ADSP_MAX_STD_CTRL_SIZE) {
Expand All @@ -110,35 +123,43 @@ static void hda_cs_dsp_add_kcontrol(struct hda_cs_dsp_coeff_ctl *ctl, const char
return;
}

ctl = kzalloc(sizeof(*ctl), GFP_KERNEL);
if (!ctl)
return;

ctl->cs_ctl = cs_ctl;
ctl->card = info->card;

kcontrol.name = name;
kcontrol.info = hda_cs_dsp_coeff_info;
kcontrol.iface = SNDRV_CTL_ELEM_IFACE_MIXER;
kcontrol.access = wmfw_convert_flags(cs_ctl->flags);
kcontrol.get = hda_cs_dsp_coeff_get;
kcontrol.put = hda_cs_dsp_coeff_put;

/* Save ctl inside private_data, ctl is owned by cs_dsp,
* and will be freed when cs_dsp removes the control */
kctl = snd_ctl_new1(&kcontrol, (void *)ctl);
if (!kctl)
return;

ret = snd_ctl_add(ctl->card, kctl);
kctl->private_free = hda_cs_dsp_free_kcontrol;
ctl->kctl = kctl;

/* snd_ctl_add() calls our private_free on error, which will kfree(ctl) */
cs_ctl->priv = no_free_ptr(ctl);
ret = snd_ctl_add(info->card, kctl);
if (ret) {
dev_err(cs_ctl->dsp->dev, "Failed to add KControl %s = %d\n", kcontrol.name, ret);
return;
}

dev_dbg(cs_ctl->dsp->dev, "Added KControl: %s\n", kcontrol.name);
ctl->kctl = kctl;
}

static void hda_cs_dsp_control_add(struct cs_dsp_coeff_ctl *cs_ctl,
const struct hda_cs_dsp_ctl_info *info)
{
struct cs_dsp *cs_dsp = cs_ctl->dsp;
char name[SNDRV_CTL_ELEM_ID_NAME_MAXLEN];
struct hda_cs_dsp_coeff_ctl *ctl;
const char *region_name;
int ret;

Expand All @@ -163,15 +184,7 @@ static void hda_cs_dsp_control_add(struct cs_dsp_coeff_ctl *cs_ctl,
" %.*s", cs_ctl->subname_len - skip, cs_ctl->subname + skip);
}

ctl = kzalloc(sizeof(*ctl), GFP_KERNEL);
if (!ctl)
return;

ctl->cs_ctl = cs_ctl;
ctl->card = info->card;
cs_ctl->priv = ctl;

hda_cs_dsp_add_kcontrol(ctl, name);
hda_cs_dsp_add_kcontrol(cs_ctl, info, name);
}

void hda_cs_dsp_add_controls(struct cs_dsp *dsp, const struct hda_cs_dsp_ctl_info *info)
Expand Down Expand Up @@ -203,7 +216,9 @@ void hda_cs_dsp_control_remove(struct cs_dsp_coeff_ctl *cs_ctl)
{
struct hda_cs_dsp_coeff_ctl *ctl = cs_ctl->priv;

kfree(ctl);
/* ctl and kctl may already have been removed by ALSA private_free */
if (ctl && ctl->kctl)
snd_ctl_remove(ctl->card, ctl->kctl);
}
EXPORT_SYMBOL_NS_GPL(hda_cs_dsp_control_remove, SND_HDA_CS_DSP_CONTROLS);

Expand Down

0 comments on commit 172811e

Please sign in to comment.