From 7ff24a4e2f97a83f3fdc2a49afd362adfa6df70f Mon Sep 17 00:00:00 2001
From: Johannes Berg <johannes.berg@intel.com>
Date: Wed, 3 Jul 2024 17:22:36 +0200
Subject: [PATCH] um: line: always fill *error_out in setup_one_line()

BugLink: https://bugs.launchpad.net/bugs/2085849

[ Upstream commit 824ac4a5edd3f7494ab1996826c4f47f8ef0f63d ]

The pointer isn't initialized by callers, but I have
encountered cases where it's still printed; initialize
it in all possible cases in setup_one_line().

Link: https://patch.msgid.link/20240703172235.ad863568b55f.Iaa1eba4db8265d7715ba71d5f6bb8c7ff63d27e9@changeid
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
CVE-2024-46844
Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com>
Signed-off-by: Roxana Nicolescu <roxana.nicolescu@canonical.com>
---
 arch/um/drivers/line.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index d82bc3fdb86e..43d8959cc746 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -383,6 +383,7 @@ int setup_one_line(struct line *lines, int n, char *init,
 			parse_chan_pair(NULL, line, n, opts, error_out);
 			err = 0;
 		}
+		*error_out = "configured as 'none'";
 	} else {
 		char *new = kstrdup(init, GFP_KERNEL);
 		if (!new) {
@@ -406,6 +407,7 @@ int setup_one_line(struct line *lines, int n, char *init,
 			}
 		}
 		if (err) {
+			*error_out = "failed to parse channel pair";
 			line->init_str = NULL;
 			line->valid = 0;
 			kfree(new);