[PATCH 3.16 079/254] ASoC: wm_adsp: Don't overrun firmware file buffer when reading region data

Ben Hutchings
2018-02-28T16:00:10Z

From: Richard Fitzgerald <rf@opensource.wolfsonmicro.com>

commit 1cab2a84f470e15ecc8e5143bfe9398c6e888032 upstream.

Protect against corrupt firmware files by ensuring that the length we
get for the data in a region actually lies within the available firmware
file data buffer.

Signed-off-by: Richard Fitzgerald <rf@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
sound/soc/codecs/wm_adsp.c | 25 ++++++++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)

--- a/sound/soc/codecs/wm_adsp.c
+++ b/sound/soc/codecs/wm_adsp.c
@@ -532,7 +532,7 @@ static int wm_adsp_load(struct wm_adsp *
const struct wmfw_region *region;
const struct wm_adsp_region *mem;
const char *region_name;
- char *file, *text;
+ char *file, *text = NULL;
struct wm_adsp_buf *buf;
unsigned int reg;
int regions = 0;
@@ -677,10 +677,21 @@ static int wm_adsp_load(struct wm_adsp *
regions, le32_to_cpu(region->len), offset,
region_name);

+ if ((pos + le32_to_cpu(region->len) + sizeof(*region)) >
+ firmware->size) {
+ adsp_err(dsp,
+ "%s.%d: %s region len %d bytes exceeds file length %zu\n",
+ file, regions, region_name,
+ le32_to_cpu(region->len), firmware->size);
+ ret = -EINVAL;
+ goto out_fw;
+ }
+
if (text) {
memcpy(text, region->data, le32_to_cpu(region->len));
adsp_info(dsp, "%s: %s\n", file, text);
kfree(text);
+ text = NULL;
}

if (reg) {
@@ -737,6 +748,7 @@ out_fw:
regmap_async_complete(regmap);
wm_adsp_buf_free(&buf_list);
release_firmware(firmware);
+ kfree(text);
out:
kfree(file);

@@ -1316,6 +1328,17 @@ static int wm_adsp_load_coeff(struct wm_
}

if (reg) {
+ if ((pos + le32_to_cpu(blk->len) + sizeof(*blk)) >
+ firmware->size) {
+ adsp_err(dsp,
+ "%s.%d: %s region len %d bytes exceeds file length %zu\n",
+ file, blocks, region_name,
+ le32_to_cpu(blk->len),
+ firmware->size);
+ ret = -EINVAL;
+ goto out_fw;
+ }
+
buf = wm_adsp_buf_alloc(blk->data,
le32_to_cpu(blk->len),
&buf_list);