firmware/imx-dsp: Fix use_after_free in imx_dsp_setup_channels()

BugLink: https://bugs.launchpad.net/bugs/2049417

[ Upstream commit 1558b1a ]

dsp_chan->name and chan_name points to same block of memory,
because dev_err still needs to be used it,so we need free
it's memory after use to avoid use_after_free.

Fixes: e527adf ("firmware: imx-dsp: Fix an error handling path in imx_dsp_setup_channels()")
Signed-off-by: Hao Ge <gehao@kylinos.cn>
Reviewed-by: Daniel Baluta <daniel.baluta@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Roxana Nicolescu <roxana.nicolescu@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Author: GeHao01994

drivers/firmware/imx/imx-dsp.c

@@ -115,11 +115,11 @@ static int imx_dsp_setup_channels(struct imx_dsp_ipc *dsp_ipc)
 		dsp_chan->idx = i % 2;
 		dsp_chan->ch = mbox_request_channel_byname(cl, chan_name);
 		if (IS_ERR(dsp_chan->ch)) {
-			kfree(dsp_chan->name);
 			ret = PTR_ERR(dsp_chan->ch);
 			if (ret != -EPROBE_DEFER)
 				dev_err(dev, "Failed to request mbox chan %s ret %d\n",
 					chan_name, ret);
+			kfree(dsp_chan->name);
 			goto out;
 		}