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authorTakashi Iwai <tiwai@suse.de>2019-07-04 16:31:12 +0200
committerTakashi Iwai <tiwai@suse.de>2019-07-05 08:06:47 +0200
commitca95c7bf3d29716916baccdc77c3c2284b703069 (patch)
tree13a802819035ac0c628b6a8e41976ba6eed842b3 /sound/usb
parent335399362a6edeec5a365ed0fbb0b6902cacc4e4 (diff)
ALSA: usb-audio: Fix parse of UAC2 Extension Units
Extension Unit (XU) is used to have a compatible layout with Processing Unit (PU) on UAC1, and the usb-audio driver code assumed it for parsing the descriptors. Meanwhile, on UAC2, XU became slightly incompatible with PU; namely, XU has a one-byte bmControls bitmap while PU has two bytes bmControls bitmap. This incompatibility results in the read of a wrong address for the last iExtension field, which ended up with an incorrect string for the mixer element name, as recently reported for Focusrite Scarlett 18i20 device. This patch corrects this misalignment by introducing a couple of new macros and calling them depending on the descriptor type. Fixes: 23caaf19b11e ("ALSA: usb-mixer: Add support for Audio Class v2.0") Reported-by: Stefan Sauer <ensonic@hora-obscura.de> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/usb')
-rw-r--r--sound/usb/mixer.c16
1 files changed, 10 insertions, 6 deletions
diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index e003b5e7b01a..ac121b10c51c 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -2318,7 +2318,7 @@ static struct procunit_info extunits[] = {
*/
static int build_audio_procunit(struct mixer_build *state, int unitid,
void *raw_desc, struct procunit_info *list,
- char *name)
+ bool extension_unit)
{
struct uac_processing_unit_descriptor *desc = raw_desc;
int num_ins;
@@ -2335,6 +2335,8 @@ static int build_audio_procunit(struct mixer_build *state, int unitid,
static struct procunit_info default_info = {
0, NULL, default_value_info
};
+ const char *name = extension_unit ?
+ "Extension Unit" : "Processing Unit";
if (desc->bLength < 13) {
usb_audio_err(state->chip, "invalid %s descriptor (id %d)\n", name, unitid);
@@ -2448,7 +2450,10 @@ static int build_audio_procunit(struct mixer_build *state, int unitid,
} else if (info->name) {
strlcpy(kctl->id.name, info->name, sizeof(kctl->id.name));
} else {
- nameid = uac_processing_unit_iProcessing(desc, state->mixer->protocol);
+ if (extension_unit)
+ nameid = uac_extension_unit_iExtension(desc, state->mixer->protocol);
+ else
+ nameid = uac_processing_unit_iProcessing(desc, state->mixer->protocol);
len = 0;
if (nameid)
len = snd_usb_copy_string_desc(state->chip,
@@ -2481,10 +2486,10 @@ static int parse_audio_processing_unit(struct mixer_build *state, int unitid,
case UAC_VERSION_2:
default:
return build_audio_procunit(state, unitid, raw_desc,
- procunits, "Processing Unit");
+ procunits, false);
case UAC_VERSION_3:
return build_audio_procunit(state, unitid, raw_desc,
- uac3_procunits, "Processing Unit");
+ uac3_procunits, false);
}
}
@@ -2495,8 +2500,7 @@ static int parse_audio_extension_unit(struct mixer_build *state, int unitid,
* Note that we parse extension units with processing unit descriptors.
* That's ok as the layout is the same.
*/
- return build_audio_procunit(state, unitid, raw_desc,
- extunits, "Extension Unit");
+ return build_audio_procunit(state, unitid, raw_desc, extunits, true);
}
/*