Commit 19317433 authored Apr 25, 2022 by Daniel Starke Committed by Greg Kroah-Hartman Apr 26, 2022

tty: n_gsm: fix sometimes uninitialized warning in gsm_dlci_modem_output()



'size' may be used uninitialized in gsm_dlci_modem_output() if called with
an adaption that is neither 1 nor 2. The function is currently only called
by gsm_modem_upd_via_data() and only for adaption 2.
Properly handle every invalid case by returning -EINVAL to silence the
compiler warning and avoid future regressions.

Fixes: c19ffe00 ("tty: n_gsm: fix invalid use of MSC in advanced option")
Cc: stable@vger.kernel.org
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220425104726.7986-1-daniel.starke@siemens.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 637674fa

drivers/tty/n_gsm.c

+9 −6

Original line number	Diff line number	Diff line
		@@ -932,18 +932,21 @@ static int gsm_dlci_modem_output(struct gsm_mux gsm, struct gsm_dlci dlci,
		{
		u8 *dp = NULL;
		struct gsm_msg *msg;
		int size;
		int size = 0;

		/* for modem bits without break data */
		if (dlci->adaption == 1) {
		size = 0;
		} else if (dlci->adaption == 2) {
		size = 1;
		switch (dlci->adaption) {
		case 1: /* Unstructured */
		break;
		case 2: /* Unstructured with modem bits. */
		size++;
		if (brk > 0)
		size++;
		} else {
		break;
		default:
		pr_err("%s: unsupported adaption %d\n", __func__,
		dlci->adaption);
		return -EINVAL;
		}

		msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);