Input: cyttsp4_core - fix use after free bug

The device md->input is used after it is released. Setting the device
data to NULL is unnecessary as the device is never used again. Instead,
md->input should be assigned NULL to avoid accessing the freed memory
accidently. Besides, checking md->si against NULL is superfluous as it
points to a variable address, which cannot be NULL.

Signed-off-by: Pan Bian <bianpan2016@163.com>
Link: https://lore.kernel.org/r/1572936379-6423-1-git-send-email-bianpan2016@163.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/touchscreen/cyttsp4_core.c b/drivers/input/touchscreen/cyttsp4_core.c
index 4b22d49..6bcffc9 100644 (file)
--- a/drivers/input/touchscreen/cyttsp4_core.c
+++ b/drivers/input/touchscreen/cyttsp4_core.c
@@ -1990,11 +1990,6 @@ static int cyttsp4_mt_probe(struct cyttsp4 *cd)
 
        /* get sysinfo */
        md->si = &cd->sysinfo;
-       if (!md->si) {
-               dev_err(dev, "%s: Fail get sysinfo pointer from core p=%p\n",
-                       __func__, md->si);
-               goto error_get_sysinfo;
-       }
 
        rc = cyttsp4_setup_input_device(cd);
        if (rc)
@@ -2004,8 +1999,6 @@ static int cyttsp4_mt_probe(struct cyttsp4 *cd)
 
 error_init_input:
        input_free_device(md->input);
-error_get_sysinfo:
-       input_set_drvdata(md->input, NULL);
 error_alloc_failed:
        dev_err(dev, "%s failed.\n", __func__);
        return rc;