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dax: fix race condition on the tuning buffer #11056

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dax: fix race condition on the tuning buffer #11056

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9fd06e9
dax: update p_dax pointer state on mock version
checkupup Jun 4, 2026
95f5201
dax: fix race condition on the tuning buffer
checkupup Jun 4, 2026
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47 changes: 35 additions & 12 deletions src/audio/module_adapter/module/dolby/dax.c
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ SOF_DEFINE_REG_UUID(dolby_dax_audio_processing);
#define DAX_CP_MASK 0x8
#define DAX_VOLUME_MASK 0x10
#define DAX_CTC_MASK 0x20
#define DAX_TUNING_FILE_MASK 0x40
#define DAX_PROCESSING_MASK 0x10000
#define DAX_RESET_MASK 0x20000
#define DAX_FREE_MASK 0x40000
Expand Down Expand Up @@ -241,24 +242,26 @@ static bool is_enabled(struct processing_module *mod)
return dax_ctx->enable && dax_ctx->p_dax;
}

static int set_tuning_file(struct processing_module *mod, void *value, uint32_t size)
static int set_tuning_file(struct processing_module *mod)
{
int ret = 0;
int ret = -EINVAL;
struct comp_dev *dev = mod->dev;
struct dax_adapter_data *adapter_data = module_get_private_data(mod);
struct sof_dax *dax_ctx = &adapter_data->dax_ctx;
k_spinlock_key_t key;

if (dax_buffer_alloc(mod, &dax_ctx->tuning_file_buffer, size) != 0) {
comp_err(dev, "allocate %u bytes failed for tuning file", size);
ret = -ENOMEM;
} else {
memcpy_s(dax_ctx->tuning_file_buffer.addr,
dax_ctx->tuning_file_buffer.free,
value,
size);
key = k_spin_lock(&adapter_data->lock);
if (adapter_data->tmp_tuning_buf.addr && adapter_data->tmp_tuning_buf.size > 0) {
dax_buffer_release(mod, &dax_ctx->tuning_file_buffer);
// Move the tmp_tuning_buf rather than copying
dax_ctx->tuning_file_buffer = adapter_data->tmp_tuning_buf;

@lyakh lyakh Aug 4, 2026

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not sure how this fixes the race... dax_buffer_release() in line 253 itself is racy - it frees directly the dax_buff->addr pointer and only then assigns NULL to it, so there's a use-after-free potential there. Also here line 254 isn't atomic - it's still the same old memcpy(), so, not very clear to me how this commit fixes any racing issues?

@checkupup checkupup Aug 4, 2026

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Uha, my bad, I miss some changes. A spinlock is added to protect access to set_tuning_file.

set_tuning_file now works in process thread which has lower thread priority than set configuration, hence I dont add a spinlock in dax_set_param_wrapper.

for dax_buffer_release(), use-after-free will not happen because tuning buffer is only used in process thread through dax_find_params interface. They are always in the same thread.

adapter_data->tmp_tuning_buf.addr = NULL;
adapter_data->tmp_tuning_buf.size = 0;
ret = 0;
}
k_spin_unlock(&adapter_data->lock, key);

comp_info(dev, "allocated: tuning %u, ret %d", dax_ctx->tuning_file_buffer.size, ret);
comp_info(dev, "apply tuning %p, ret %d", dax_ctx->tuning_file_buffer.addr, ret);
return ret;
}

Expand Down Expand Up @@ -367,7 +370,19 @@ static int dax_set_param_wrapper(struct processing_module *mod,

switch (id) {
case DAX_PARAM_ID_TUNING_FILE:
set_tuning_file(mod, value, size);
if (dax_buffer_alloc(mod, &adapter_data->tmp_tuning_buf, size) != 0) {
comp_err(dev, "allocate %u bytes failed for tuning file", size);
ret = -ENOMEM;
} else {
memcpy_s(adapter_data->tmp_tuning_buf.addr,
adapter_data->tmp_tuning_buf.free,
value,
size);
flag_process(adapter_data, DAX_TUNING_FILE_MASK, DAX_FLAG_SET);
comp_info(dev, "allocated: tuning %p, size %u",
adapter_data->tmp_tuning_buf.addr,
adapter_data->tmp_tuning_buf.size);
}
break;
case DAX_PARAM_ID_ENABLE:
tmp_val = *((int32_t *)value);
Expand Down Expand Up @@ -488,6 +503,12 @@ static void check_and_update_settings(struct processing_module *mod)
if (!is_enabled(mod))
return;

if (flag_process(adapter_data, DAX_TUNING_FILE_MASK, DAX_FLAG_READ_AND_CLEAR)) {
set_tuning_file(mod);
flag_process(adapter_data, DAX_DEVICE_MASK, DAX_FLAG_SET);
flag_process(adapter_data, DAX_VOLUME_MASK, DAX_FLAG_SET);
}

if (flag_process(adapter_data, DAX_DEVICE_MASK, DAX_FLAG_READ_AND_CLEAR)) {
set_device(mod, dax_ctx->out_device);
set_tuning_device(mod, dax_ctx->tuning_device);
Expand Down Expand Up @@ -547,6 +568,7 @@ static int sof_dax_free(struct processing_module *mod)
dax_buffer_release(mod, &dax_ctx->tuning_file_buffer);
mod_data_blob_handler_free(mod, dax_ctx->blob_handler);
dax_ctx->blob_handler = NULL;
dax_buffer_release(mod, &adapter_data->tmp_tuning_buf);
mod_free(mod, adapter_data);
module_set_private_data(mod, NULL);
}
Expand Down Expand Up @@ -584,6 +606,7 @@ static int sof_dax_init(struct processing_module *mod)
adapter_data = module_get_private_data(mod);
adapter_data->comp_id = dev->ipc_config.id;
adapter_data->priority = DAX_USER_PRIORITY_DEFAULT;
k_spinlock_init(&adapter_data->lock);
dax_ctx = &adapter_data->dax_ctx;
dax_ctx->enable = 0;
dax_ctx->profile = 0;
Expand Down
3 changes: 3 additions & 0 deletions src/audio/module_adapter/module/dolby/dax.h
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
* Author: Jun Lai <jun.lai@dolby.com>
*/

#include <rtos/spinlock.h>
#include <sof/audio/module_adapter/module/generic.h>
#include <dax_inf.h>

Expand All @@ -24,6 +25,8 @@ struct dax_adapter_data {
atomic_t proc_flags;
uint32_t comp_id;
int32_t priority;
struct dax_buffer tmp_tuning_buf;
struct k_spinlock lock;
};

/**
Expand Down
4 changes: 3 additions & 1 deletion src/audio/module_adapter/module/dolby/dax_mock.c
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Original file line number Diff line number Diff line change
Expand Up @@ -29,11 +29,13 @@ uint32_t dax_query_period_frames(struct sof_dax *dax_ctx)

int dax_free(struct sof_dax *dax_ctx)
{
dax_ctx->p_dax = NULL;
return 0;
}

int dax_init(struct sof_dax *dax_ctx)
{
dax_ctx->p_dax = dax_ctx->persist_buffer.addr;
return 0;
}

Expand Down Expand Up @@ -81,7 +83,7 @@ int dax_set_ctc_enable(int32_t enable, struct sof_dax *dax_ctx)

const char *dax_get_version(void)
{
return "";
return "mock_version";
}

void *dax_find_params(uint32_t query_id,
Expand Down
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