[PATCH 20/32] ASoC: sigmadsp: Use mem_to_flex_dup() with struct sigmadsp_data

[Kees Cook <keescook@xxxxxxxxxxxx>]

As part of the work to perform bounds checking on all memcpy() uses,
replace the open-coded a deserialization of bytes out of memory into a
trailing flexible array by using a flex_array.h helper to perform the
allocation, bounds checking, and copying.

Cc: Lars-Peter Clausen <lars@xxxxxxxxxx>
Cc: "Nuno Sá" <nuno.sa@xxxxxxxxxx>
Cc: Liam Girdwood <lgirdwood@xxxxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxx>
Cc: Jaroslav Kysela <perex@xxxxxxxx>
Cc: Takashi Iwai <tiwai@xxxxxxxx>
Cc: alsa-devel@xxxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 sound/soc/codecs/sigmadsp.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/sound/soc/codecs/sigmadsp.c b/sound/soc/codecs/sigmadsp.c
index b992216aee55..648bdc73c5d9 100644
--- a/sound/soc/codecs/sigmadsp.c
+++ b/sound/soc/codecs/sigmadsp.c
@@ -42,8 +42,8 @@ struct sigmadsp_data {
        struct list_head head;
        uint32_t samplerates;
        unsigned int addr;
-       unsigned int length;
-       uint8_t data[];
+       DECLARE_FLEX_ARRAY_ELEMENTS_COUNT(unsigned int, length);
+       DECLARE_FLEX_ARRAY_ELEMENTS(uint8_t, data);
 };
 
 struct sigma_fw_chunk {
@@ -263,7 +263,7 @@ static int sigma_fw_load_data(struct sigmadsp *sigmadsp,
        const struct sigma_fw_chunk *chunk, unsigned int length)
 {
        const struct sigma_fw_chunk_data *data_chunk;
-       struct sigmadsp_data *data;
+       struct sigmadsp_data *data = NULL;
 
        if (length <= sizeof(*data_chunk))
                return -EINVAL;
@@ -272,14 +272,11 @@ static int sigma_fw_load_data(struct sigmadsp *sigmadsp,
 
        length -= sizeof(*data_chunk);
 
-       data = kzalloc(sizeof(*data) + length, GFP_KERNEL);
-       if (!data)
+       if (mem_to_flex_dup(&data, data_chunk->data, length, GFP_KERNEL))
                return -ENOMEM;
 
        data->addr = le16_to_cpu(data_chunk->addr);
-       data->length = length;
        data->samplerates = le32_to_cpu(chunk->samplerates);
-       memcpy(data->data, data_chunk->data, length);
        list_add_tail(&data->head, &sigmadsp->data_list);
 
        return 0;
-- 
2.32.0