Add a check to cs_dsp_coeff_write_ctrl() to abort if the control
is not writeable.
The cs_dsp code originated as an ASoC driver (wm_adsp) where all
controls were exported as ALSA controls. It relied on ALSA to
enforce the read-only permission. Now that the code has been
separated from ALSA/ASoC it must perform its own permission check.
This isn't currently causing any problems so there shouldn't be any
need to backport this. If the client of cs_dsp exposes the control as
an ALSA control, it should set permissions on that ALSA control to
protect it. The few uses of cs_dsp_coeff_write_ctrl() inside drivers
are for writable controls.
Signed-off-by: Richard Fitzgerald <rf@xxxxxxxxxxxxxxxxxxxxx>
---
drivers/firmware/cirrus/cs_dsp.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/firmware/cirrus/cs_dsp.c b/drivers/firmware/cirrus/cs_dsp.c
index 16484ab9b09d..be8747d227db 100644
--- a/drivers/firmware/cirrus/cs_dsp.c
+++ b/drivers/firmware/cirrus/cs_dsp.c
@@ -796,6 +796,9 @@ int cs_dsp_coeff_write_ctrl(struct cs_dsp_coeff_ctl *ctl,
lockdep_assert_held(&ctl->dsp->pwr_lock);
+ if (ctl->flags && !(ctl->flags & WMFW_CTL_FLAG_WRITEABLE))
+ return -EPERM;
+
if (len + off * sizeof(u32) > ctl->len)
return -EINVAL;
--
2.39.2
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