[PATCH 4.19 073/168] media: firewire: Using uninitialized values in node_probe()

[Greg Kroah-Hartman]

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

[ Upstream commit 2505a210fc126599013aec2be741df20aaacc490 ]

If fw_csr_string() returns -ENOENT, then "name" is uninitialized.  So
then the "strlen(model_names[i]) <= name_len" is true because strlen()
is unsigned and -ENOENT is type promoted to a very high positive value.
Then the "strncmp(name, model_names[i], name_len)" uses uninitialized
data because "name" is uninitialized.

Fixes: 92374e886c75 ("[media] firedtv: drop obsolete backend abstraction")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/media/firewire/firedtv-fw.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/media/firewire/firedtv-fw.c b/drivers/media/firewire/firedtv-fw.c
index 92f4112d2e377..eaf94b817dbc0 100644
--- a/drivers/media/firewire/firedtv-fw.c
+++ b/drivers/media/firewire/firedtv-fw.c
@@ -271,6 +271,8 @@ static int node_probe(struct fw_unit *unit, const struct ieee1394_device_id *id)
 
 	name_len = fw_csr_string(unit->directory, CSR_MODEL,
 				 name, sizeof(name));
+	if (name_len < 0)
+		return name_len;
 	for (i = ARRAY_SIZE(model_names); --i; )
 		if (strlen(model_names[i]) <= name_len &&
 		    strncmp(name, model_names[i], name_len) == 0)
-- 
2.25.1