[PATCH] ASoC: SOF: Add some bounds checking to firmware data

[Dan Carpenter <dan.carpenter@linaro.org>]

Smatch complains about "head->full_size - head->header_size" can
underflow.  To some extent, we're always going to have to trust the
firmware a bit.  However, it's easy enough to add a check for negatives,
and let's add a upper bounds check as well.

Fixes: d2458baa799f ("ASoC: SOF: ipc3-loader: Implement firmware parsing and loading")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
 sound/soc/sof/ipc3-loader.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sound/soc/sof/ipc3-loader.c b/sound/soc/sof/ipc3-loader.c
index 28218766d211..6e3ef0672110 100644
--- a/sound/soc/sof/ipc3-loader.c
+++ b/sound/soc/sof/ipc3-loader.c
@@ -148,6 +148,8 @@ static size_t sof_ipc3_fw_parse_ext_man(struct snd_sof_dev *sdev)
 
 	head = (struct sof_ext_man_header *)fw->data;
 	remaining = head->full_size - head->header_size;
+	if (remaining < 0 || remaining > sdev->basefw.fw->size)
+		return -EINVAL;
 	ext_man_size = ipc3_fw_ext_man_size(sdev, fw);
 
 	/* Assert firmware starts with extended manifest */
-- 
2.43.0