[PATCH 4.9 10/78] ALSA: hda: prevent undefined shift in snd_hdac_ext_bus_get_link()

Greg Kroah-Hartman
2020-11-17T13:09:52Z

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit 158e1886b6262c1d1c96a18c85fac5219b8bf804 ]

This is harmless, but the "addr" comes from the user and it could lead
to a negative shift or to shift wrapping if it's too high.

Fixes: 0b00a5615dc4 ("ALSA: hdac_ext: add hdac extended controller")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20201103101807.GC1127762@mwanda
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
sound/hda/ext/hdac_ext_controller.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/sound/hda/ext/hdac_ext_controller.c b/sound/hda/ext/hdac_ext_controller.c
index 261469188566c..49d42971d90da 100644
--- a/sound/hda/ext/hdac_ext_controller.c
+++ b/sound/hda/ext/hdac_ext_controller.c
@@ -155,6 +155,8 @@ struct hdac_ext_link *snd_hdac_ext_bus_get_link(struct hdac_ext_bus *ebus,
return NULL;
if (ebus->idx != bus_idx)
return NULL;
+ if (addr < 0 || addr > 31)
+ return NULL;

list_for_each_entry(hlink, &ebus->hlink_list, list) {
for (i = 0; i < HDA_MAX_CODECS; i++) {
--
2.27.0