ALSA: hda: prevent undefined shift in snd_hdac_ext_bus_get_link()

BugLink: https://bugs.launchpad.net/bugs/1905618
[ 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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/sound/hda/ext/hdac_ext_controller.c b/sound/hda/ext/hdac_ext_controller.c
index 09ff209df4a30faead7d760c9a8bc4be1ea891b3..c87187f63573302b8582be48690bcc4e352b816d 100644 (file)
--- a/sound/hda/ext/hdac_ext_controller.c
+++ b/sound/hda/ext/hdac_ext_controller.c
@@ -148,6 +148,8 @@ struct hdac_ext_link *snd_hdac_ext_bus_get_link(struct hdac_bus *bus,
                return NULL;
        if (bus->idx != bus_idx)
                return NULL;
+       if (addr < 0 || addr > 31)
+               return NULL;
 
        list_for_each_entry(hlink, &bus->hlink_list, list) {
                for (i = 0; i < HDA_MAX_CODECS; i++) {