2021-10-26 12:58:08

by Johan Hovold

Subject: [PATCH] sound: ua101: fix division by zero at probe

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: [email protected] # 2.6.34
Signed-off-by: Johan Hovold <[email protected]>
---
sound/usb/misc/ua101.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/usb/misc/ua101.c b/sound/usb/misc/ua101.c
index 5834d1dc317e..4f6b20ed29dd 100644
--- a/sound/usb/misc/ua101.c
+++ b/sound/usb/misc/ua101.c
@@ -1000,7 +1000,7 @@ static int detect_usb_format(struct ua101 *ua)
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;
}
@@ -1008,7 +1008,7 @@ static int detect_usb_format(struct ua101 *ua)
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;
}
--
2.32.0

2021-10-27 18:23:13

by Takashi Iwai

Subject: Re: [PATCH] sound: ua101: fix division by zero at probe

On Tue, 26 Oct 2021 11:54:01 +0200,
Johan Hovold wrote:
>
> 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: [email protected] # 2.6.34
> Signed-off-by: Johan Hovold <[email protected]>

Thanks, applied.


Takashi