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authorTakashi Iwai <tiwai@suse.de>2017-09-22 16:18:53 +0200
committerTakashi Iwai <tiwai@suse.de>2017-09-22 16:21:31 +0200
commitbfc81a8bc18e3c4ba0cbaa7666ff76be2f998991 (patch)
tree40f792e955bd6426dd9844a795efeb474a6e5c3f /sound
parentc9adcdbc653b52e4be834f535eefec833f9ca6b1 (diff)
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ALSA: usb-audio: Check out-of-bounds access by corrupted buffer descriptor
When a USB-audio device receives a maliciously adjusted or corrupted buffer descriptor, the USB-audio driver may access an out-of-bounce value at its parser. This was detected by syzkaller, something like: BUG: KASAN: slab-out-of-bounds in usb_audio_probe+0x27b2/0x2ab0 Read of size 1 at addr ffff88006b83a9e8 by task kworker/0:1/24 CPU: 0 PID: 24 Comm: kworker/0:1 Not tainted 4.14.0-rc1-42251-gebb2c2437d80 #224 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Workqueue: usb_hub_wq hub_event Call Trace: __dump_stack lib/dump_stack.c:16 dump_stack+0x292/0x395 lib/dump_stack.c:52 print_address_description+0x78/0x280 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 kasan_report+0x22f/0x340 mm/kasan/report.c:409 __asan_report_load1_noabort+0x19/0x20 mm/kasan/report.c:427 snd_usb_create_streams sound/usb/card.c:248 usb_audio_probe+0x27b2/0x2ab0 sound/usb/card.c:605 usb_probe_interface+0x35d/0x8e0 drivers/usb/core/driver.c:361 really_probe drivers/base/dd.c:413 driver_probe_device+0x610/0xa00 drivers/base/dd.c:557 __device_attach_driver+0x230/0x290 drivers/base/dd.c:653 bus_for_each_drv+0x161/0x210 drivers/base/bus.c:463 __device_attach+0x26e/0x3d0 drivers/base/dd.c:710 device_initial_probe+0x1f/0x30 drivers/base/dd.c:757 bus_probe_device+0x1eb/0x290 drivers/base/bus.c:523 device_add+0xd0b/0x1660 drivers/base/core.c:1835 usb_set_configuration+0x104e/0x1870 drivers/usb/core/message.c:1932 generic_probe+0x73/0xe0 drivers/usb/core/generic.c:174 usb_probe_device+0xaf/0xe0 drivers/usb/core/driver.c:266 really_probe drivers/base/dd.c:413 driver_probe_device+0x610/0xa00 drivers/base/dd.c:557 __device_attach_driver+0x230/0x290 drivers/base/dd.c:653 bus_for_each_drv+0x161/0x210 drivers/base/bus.c:463 __device_attach+0x26e/0x3d0 drivers/base/dd.c:710 device_initial_probe+0x1f/0x30 drivers/base/dd.c:757 bus_probe_device+0x1eb/0x290 drivers/base/bus.c:523 device_add+0xd0b/0x1660 drivers/base/core.c:1835 usb_new_device+0x7b8/0x1020 drivers/usb/core/hub.c:2457 hub_port_connect drivers/usb/core/hub.c:4903 hub_port_connect_change drivers/usb/core/hub.c:5009 port_event drivers/usb/core/hub.c:5115 hub_event+0x194d/0x3740 drivers/usb/core/hub.c:5195 process_one_work+0xc7f/0x1db0 kernel/workqueue.c:2119 worker_thread+0x221/0x1850 kernel/workqueue.c:2253 kthread+0x3a1/0x470 kernel/kthread.c:231 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431 This patch adds the checks of out-of-bounce accesses at appropriate places and bails out when it goes out of the given buffer. Reported-by: Andrey Konovalov <andreyknvl@google.com> Tested-by: Andrey Konovalov <andreyknvl@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound')
-rw-r--r--sound/usb/card.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/sound/usb/card.c b/sound/usb/card.c
index 3dc36d913550..23d1d23aefec 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 +236,15 @@ 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;
+
+ /* just to be sure -- this shouldn't hit at all */
+ if (rest_bytes <= 0) {
+ dev_err(&dev->dev, "invalid control header\n");
+ return -EINVAL;
+ }
+
switch (protocol) {
default:
dev_warn(&dev->dev,
@@ -245,11 +255,21 @@ 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;