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ALSA: usb-audio: Always check descriptor sizes in parser code 

commit 3e96d7280f16e2f787307f695a31296b9e4a1cd7 upstream.

There are a few places where we access the data without checking the
actual object size from the USB audio descriptor.  This may result in
OOB access, as recently reported.

This patch addresses these missing checks.  Most of added codes are
simple bLength checks in the caller side.  For the input and output
terminal parsers, we put the length check in the parser functions.
For the input terminal, a new argument is added to distinguish between
UAC1 and the rest, as they treat different objects.

Reported-by: Mathias Payer <mathias.payer@nebelwelt.net>
Reported-by: Hui Peng <benquike@163.com>
Tested-by: Hui Peng <benquike@163.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
[bwh: Backported to 3.16:
 - Drop changes in parse_audio_input_terminal() and UAC3 handling
 - Adjust context, indentation]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
This commit is contained in:
Takashi Iwai 2019-01-02 17:12:21 +01:00 committed by syphyr
parent 05e00017c0
commit 4e545f2462
2 changed files with 27 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
sound/usb/card.c
View File

@ -271,6 +271,11 @@ static int snd_usb_create_streams(struct snd_usb_audio *chip, int ctrlif)
return -EINVAL;
}
if (h1->bLength < sizeof(*h1)) {
dev_err(&dev->dev, "cannot find UAC_HEADER\n");
return -EINVAL;
}
if (!h1->bInCollection) {
snd_printk(KERN_INFO "skipping empty audio interface (v1)\n");
return -EINVAL;

33
sound/usb/stream.c
View File

@ -404,13 +404,8 @@ static int parse_uac_endpoint_attributes(struct snd_usb_audio *chip,
csep = snd_usb_find_desc(alts->extra, alts->extralen, NULL, USB_DT_CS_ENDPOINT);
if (!csep || csep->bLength < 7 ||
csep->bDescriptorSubtype != UAC_EP_GENERAL) {
snd_printk(KERN_WARNING "%d:%u:%d : no or invalid"
" class specific endpoint descriptor\n",
chip->dev->devnum, iface_no,
altsd->bAlternateSetting);
return 0;
}
csep->bDescriptorSubtype != UAC_EP_GENERAL)
goto error;
if (protocol == UAC_VERSION_1) {
attributes = csep->bmAttributes;
@ -418,6 +413,8 @@ static int parse_uac_endpoint_attributes(struct snd_usb_audio *chip,
struct uac2_iso_endpoint_descriptor *csep2 =
(struct uac2_iso_endpoint_descriptor *) csep;
if (csep2->bLength < sizeof(*csep2))
goto error;
attributes = csep->bmAttributes & UAC_EP_CS_ATTR_FILL_MAX;
/* emulate the endpoint attributes of a v1 device */
@ -426,6 +423,13 @@ static int parse_uac_endpoint_attributes(struct snd_usb_audio *chip,
}
return attributes;
error:
snd_printk(KERN_WARNING "%d:%u:%d : no or invalid"
" class specific endpoint descriptor\n",
chip->dev->devnum, iface_no,
altsd->bAlternateSetting);
return 0;
}
/* find an input terminal descriptor (either UAC1 or UAC2) with the given
@ -433,13 +437,17 @@ static int parse_uac_endpoint_attributes(struct snd_usb_audio *chip,
*/
static void *
snd_usb_find_input_terminal_descriptor(struct usb_host_interface *ctrl_iface,
int terminal_id)
int terminal_id, bool uac2)
{
struct uac2_input_terminal_descriptor *term = NULL;
size_t minlen = uac2 ? sizeof(struct uac2_input_terminal_descriptor) :
sizeof(struct uac_input_terminal_descriptor);
while ((term = snd_usb_find_csint_desc(ctrl_iface->extra,
ctrl_iface->extralen,
term, UAC_INPUT_TERMINAL))) {
if (term->bLength < minlen)
continue;
if (term->bTerminalID == terminal_id)
return term;
}
@ -456,7 +464,8 @@ static struct uac2_output_terminal_descriptor *
while ((term = snd_usb_find_csint_desc(ctrl_iface->extra,
ctrl_iface->extralen,
term, UAC_OUTPUT_TERMINAL))) {
if (term->bTerminalID == terminal_id)
if (term->bLength >= sizeof(*term) &&
term->bTerminalID == terminal_id)
return term;
}
@ -543,7 +552,8 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
format = le16_to_cpu(as->wFormatTag); /* remember the format value */
iterm = snd_usb_find_input_terminal_descriptor(chip->ctrl_intf,
as->bTerminalLink);
as->bTerminalLink,
false);
if (iterm) {
num_channels = iterm->bNrChannels;
chconfig = le16_to_cpu(iterm->wChannelConfig);
@ -576,7 +586,8 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
/* lookup the terminal associated to this interface
* to extract the clock */
input_term = snd_usb_find_input_terminal_descriptor(chip->ctrl_intf,
as->bTerminalLink);
as->bTerminalLink,
true);
if (input_term) {
clock = input_term->bCSourceID;
chconfig = le32_to_cpu(input_term->bmChannelConfig);