ACK: [PATCH] ALSA: usb-audio: Check out-of-bounds access by corrupted buffer descriptor
Stefan Bader
stefan.bader at canonical.com
Thu Jul 19 14:31:47 UTC 2018
On 19.07.2018 16:27, Paolo Pisati wrote:
> From: Takashi Iwai <tiwai at suse.de>
>
> 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 at google.com>
> Tested-by: Andrey Konovalov <andreyknvl at google.com>
> Cc: <stable at vger.kernel.org>
> Signed-off-by: Takashi Iwai <tiwai at suse.de>
> (cherry picked from commit bfc81a8bc18e3c4ba0cbaa7666ff76be2f998991)
> Signed-off-by: Paolo Pisati <paolo.pisati at canonical.com>
Acked-by: Stefan Bader <stefan.bader at canonical.com>
> ---
> sound/usb/card.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/sound/usb/card.c b/sound/usb/card.c
> index ab433a0..9189dbc 100644
> --- a/sound/usb/card.c
> +++ b/sound/usb/card.c
> @@ -218,6 +218,7 @@ 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];
> @@ -232,6 +233,15 @@ 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:
> snd_printdd(KERN_WARNING "unknown interface protocol %#02x, assuming v1\n",
> @@ -241,11 +251,21 @@ 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) {
> snd_printk(KERN_INFO "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) {
> snd_printk(KERN_ERR "invalid UAC_HEADER (v1)\n");
> return -EINVAL;
>
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