On Fri, 22 Sep 2017 14:56:06 +0200,
Andrey Konovalov wrote:
>
> Hi!
>
> I've got the following report while fuzzing the kernel with syzkaller.
>
> On commit ebb2c2437d8008d46796902ff390653822af6cc4 (Sep 18).
>
> It seems that there's no check that control_header has enough space
> for uac1_ac_header_descriptor in snd_usb_create_streams().
Indeed, this might be an issue.
Does the patch below fix the problem?
Takashi
---
diff --git a/sound/usb/card.c b/sound/usb/card.c
index 3dc36d913550..fc969efbb37c 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -221,6 +221,7 @@ static int snd_usb_create_streams(struct snd_usb_audio *chip, int ctrlif)
struct usb_interface_descriptor *altsd;
void *control_header;
int i, protocol;
+ int rest_bytes;
/* find audiocontrol interface */
host_iface = &usb_ifnum_to_if(dev, ctrlif)->altsetting[0];
@@ -235,6 +236,13 @@ static int snd_usb_create_streams(struct snd_usb_audio *chip, int ctrlif)
return -EINVAL;
}
+ rest_bytes = (void *)(host_iface->extra + host_iface->extralen) -
+ control_header;
+ if (rest_bytes <= 0) {
+ dev_err(&dev->dev, "invalid control header\n");
+ return -EINVAL;
+ }
+
switch (protocol) {
default:
dev_warn(&dev->dev,
@@ -245,11 +253,21 @@ static int snd_usb_create_streams(struct snd_usb_audio *chip, int ctrlif)
case UAC_VERSION_1: {
struct uac1_ac_header_descriptor *h1 = control_header;
+ if (rest_bytes < sizeof(*h1)) {
+ dev_err(&dev->dev, "too short v1 buffer descriptor\n");
+ return -EINVAL;
+ }
+
if (!h1->bInCollection) {
dev_info(&dev->dev, "skipping empty audio interface (v1)\n");
return -EINVAL;
}
+ if (rest_bytes < h1->bLength) {
+ dev_err(&dev->dev, "invalid buffer length (v1)\n");
+ return -EINVAL;
+ }
+
if (h1->bLength < sizeof(*h1) + h1->bInCollection) {
dev_err(&dev->dev, "invalid UAC_HEADER (v1)\n");
return -EINVAL;
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