firmware: cs_dsp: Fix overrun of unterminated control name string

For wmfw format v2 and later the coefficient name strings have a length
field and are NOT null-terminated. Use kasprintf() to convert the
unterminated string into a null-terminated string in an allocated buffer.

The previous code handled this duplication incorrectly using kmemdup()
and getting the length from a strlen() of the (unterminated) source string.
This resulted in creating a string that continued up to the next byte in
the firmware file that just happened to be 0x00.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Fixes: f6bc909e7673 ("firmware: cs_dsp: add driver to support firmware loading on Cirrus Logic DSPs")
Link: https://lore.kernel.org/r/20220412163927.1303470-1-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/firmware/cirrus/cs_dsp.c b/drivers/firmware/cirrus/cs_dsp.c
index e48108e694f8dcb08f5e91fcb2d89de9a78946a7..7dad6f57d97042cc1a13b48a58c58e3938465e0f 100644 (file)
--- a/drivers/firmware/cirrus/cs_dsp.c
+++ b/drivers/firmware/cirrus/cs_dsp.c
@@ -955,8 +955,7 @@ static int cs_dsp_create_control(struct cs_dsp *dsp,
        ctl->alg_region = *alg_region;
        if (subname && dsp->fw_ver >= 2) {
                ctl->subname_len = subname_len;
-               ctl->subname = kmemdup(subname,
-                                      strlen(subname) + 1, GFP_KERNEL);
+               ctl->subname = kasprintf(GFP_KERNEL, "%.*s", subname_len, subname);
                if (!ctl->subname) {
                        ret = -ENOMEM;
                        goto err_ctl;