[PATCH 3/4] Input: cyapa - Allow filename to be changed in update_fw

[Benson Leung <bleung@chromium.org>]

Allow the name of the designated firmware to be passed as the
argument to update_fw from user space. This will allow user space
to specify which firmware to load.

Signed-off-by: Benson Leung <bleung@chromium.org>
---
 drivers/input/mouse/cyapa.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/input/mouse/cyapa.c b/drivers/input/mouse/cyapa.c
index e622c25..51e9d44 100644
--- a/drivers/input/mouse/cyapa.c
+++ b/drivers/input/mouse/cyapa.c
@@ -1180,9 +1180,16 @@ static ssize_t cyapa_update_fw_store(struct device *dev,
 				     const char *buf, size_t count)
 {
 	struct cyapa *cyapa = dev_get_drvdata(dev);
-	const char *fw_name = CYAPA_FW_NAME;
+	const char *fw_name;
 	int ret;
 
+	/* Do not allow paths that step out of /lib/firmware  */
+	if (strstr(buf, "../") != NULL)
+		return -EINVAL;
+
+	fw_name = !strncmp(buf, "1", count) ||
+		  !strncmp(buf, "1\n", count) ? CYAPA_FW_NAME : buf;
+
 	ret = cyapa_firmware(cyapa, fw_name);
 	if (ret)
 		dev_err(dev, "firmware update failed, %d\n", ret);
-- 
1.8.1.3