[alsa-devel] [PATCH 2/2] ALSA: usb-audio: Add sanity checks in v3 clock parsers

[Takashi Iwai]

The UAC3 clock parser codes lack of the sanity checks for malformed
descriptors like UAC2 parser does.  Without it, the driver may lead to
a potential crash.

Fixes: 9a2fe9b801f5 ("ALSA: usb: initial USB Audio Device Class 3.0 support")
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 sound/usb/clock.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/sound/usb/clock.c b/sound/usb/clock.c
index c5f0cf532c0c..169fb3ac3715 100644
--- a/sound/usb/clock.c
+++ b/sound/usb/clock.c
@@ -58,7 +58,7 @@ static bool validate_clock_source_v2(void *p, int id)
 static bool validate_clock_source_v3(void *p, int id)
 {
 	struct uac3_clock_source_descriptor *cs = p;
-	return cs->bClockID == id;
+	return cs->bLength >= sizeof(*cs) && cs->bClockID == id;
 }
 
 static bool validate_clock_selector_v2(void *p, int id)
@@ -71,7 +71,8 @@ static bool validate_clock_selector_v2(void *p, int id)
 static bool validate_clock_selector_v3(void *p, int id)
 {
 	struct uac3_clock_selector_descriptor *cs = p;
-	return cs->bClockID == id;
+	return cs->bLength >= sizeof(*cs) && cs->bClockID == id &&
+		cs->bLength >= 5 + cs->bNrInPins;
 }
 
 static bool validate_clock_multiplier_v2(void *p, int id)
@@ -83,7 +84,7 @@ static bool validate_clock_multiplier_v2(void *p, int id)
 static bool validate_clock_multiplier_v3(void *p, int id)
 {
 	struct uac3_clock_multiplier_descriptor *cs = p;
-	return cs->bClockID == id;
+	return cs->bLength >= sizeof(*cs) && cs->bClockID == id;
 }
 
 #define DEFINE_FIND_HELPER(name, obj, validator, type)		\
-- 
2.16.2