[PATCH 4.9 011/207] ALSA: ua101: fix division by zero at probe

[Greg Kroah-Hartman]

From: Johan Hovold <johan@xxxxxxxxxx>

commit 55f261b73a7e1cb254577c3536cef8f415de220a upstream.

Add the missing endpoint max-packet sanity check to probe() to avoid
division by zero in alloc_stream_buffers() in case a malicious device
has broken descriptors (or when doing descriptor fuzz testing).

Note that USB core will reject URBs submitted for endpoints with zero
wMaxPacketSize but that drivers doing packet-size calculations still
need to handle this (cf. commit 2548288b4fb0 ("USB: Fix: Don't skip
endpoint descriptors with maxpacket=0")).

Fixes: 63978ab3e3e9 ("sound: add Edirol UA-101 support")
Cc: stable@xxxxxxxxxxxxxxx      # 2.6.34
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20211026095401.26522-1-johan@xxxxxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 sound/usb/misc/ua101.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/sound/usb/misc/ua101.c
+++ b/sound/usb/misc/ua101.c
@@ -1032,7 +1032,7 @@ static int detect_usb_format(struct ua10
 		fmt_playback->bSubframeSize * ua->playback.channels;
 
 	epd = &ua->intf[INTF_CAPTURE]->altsetting[1].endpoint[0].desc;
-	if (!usb_endpoint_is_isoc_in(epd)) {
+	if (!usb_endpoint_is_isoc_in(epd) || usb_endpoint_maxp(epd) == 0) {
 		dev_err(&ua->dev->dev, "invalid capture endpoint\n");
 		return -ENXIO;
 	}
@@ -1040,7 +1040,7 @@ static int detect_usb_format(struct ua10
 	ua->capture.max_packet_bytes = usb_endpoint_maxp(epd);
 
 	epd = &ua->intf[INTF_PLAYBACK]->altsetting[1].endpoint[0].desc;
-	if (!usb_endpoint_is_isoc_out(epd)) {
+	if (!usb_endpoint_is_isoc_out(epd) || usb_endpoint_maxp(epd) == 0) {
 		dev_err(&ua->dev->dev, "invalid playback endpoint\n");
 		return -ENXIO;
 	}