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Baul Lee f1fbb50b99 ALSA: usb-audio: fix OOB write on Type II inbound URBs
commit 69ee44e1a2 upstream.

data_ep_set_params() sizes each URB transfer buffer before it adds the
Format Type II transfer delimiter:

	u->packets = urb_packs;
	u->buffer_size = maxsize * u->packets;

	if (fmt->fmt_type == UAC_FORMAT_TYPE_II)
		u->packets++; /* for transfer delimiter */
	u->urb = usb_alloc_urb(u->packets, GFP_KERNEL);

buffer_size is computed from the pre-increment packet count and never
recomputed, so for a Type II endpoint the buffer is one packet short of
the packet count the URB is built with.

prepare_inbound_urb() then lays out one iso frame per packet and never
consults buffer_size:

	offs = 0;
	for (i = 0; i < urb_ctx->packets; i++) {
		urb->iso_frame_desc[i].offset = offs;
		urb->iso_frame_desc[i].length = ep->curpacksize;
		offs += ep->curpacksize;
	}

	urb->transfer_buffer_length = offs;
	urb->number_of_packets = urb_ctx->packets;

The last descriptor therefore points one packet past the end of the
transfer buffer, where the host controller writes device data on every
inbound transfer.  prepare_silent_urb() and prepare_playback_urb() bound
their fill loops by ctx->buffer_size, so only capture is affected.

fmt_type comes from the device's audio streaming descriptors, so any
device advertising a Type II capture format hits this once userspace sets
hw_params on the stream.

KASAN on 7.2.0-rc5 (arm64) with a dummy_hcd/raw-gadget device, one report
per inbound transfer:

  BUG: KASAN: slab-out-of-bounds in dummy_timer
  Write of size 64 at addr ffff0000186171c0 by task cons02/166
   __asan_memcpy
   dummy_timer
   hrtimer_run_softirq
  Allocated by task 166:
   usb_alloc_coherent
   snd_usb_endpoint_set_params
  The buggy address is located 0 bytes to the right of
   allocated 64-byte region [ffff000018617180, ffff0000186171c0)

Compute buffer_size after the delimiter packet has been accounted for,
and bound the fill loop by buffer_size, as prepare_silent_urb() already
does on the outbound side.  This grows every Type II URB allocation by
one maxsize packet.

Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>

Fixes: 8fdff6a319 ("ALSA: snd-usb: implement new endpoint streaming model")
Reported-by: Federico Kirschbaum <federico.kirschbaum@xbow.com>
Reported-by: Baul Lee <baul.lee@xbow.com>
Cc: stable@vger.kernel.org
Signed-off-by: Baul Lee <baul.lee@xbow.com>
Link: https://patch.msgid.link/20260805013441.38245-1-baul.lee@xbow.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2026-08-19 17:14:14 +02:00
arch ARM: npcm: Fix OF node refcount leaks in SMP setup 2026-08-19 17:14:13 +02:00
block partitions: aix: bound the pp_count scan to the ppe array 2026-07-24 15:51:24 +02:00
certs X.509: Fix validation of ASN.1 certificate header 2026-07-24 15:51:59 +02:00
crypto crypto: rsa-pkcs1pad: Don't WARN on an empty digest 2026-08-19 17:13:55 +02:00
Documentation PCI: Move Resizable BAR code to rebar.c 2026-07-24 15:51:58 +02:00
drivers Input: evdev - sanitize event type index when fetching event masks 2026-08-19 17:14:14 +02:00
fs NFS: Pin the 'struct nfs_server' during a FREE_STATEID call 2026-08-19 17:14:13 +02:00
include dmaengine: qcom: bam_dma: Fix command element mask field for BAM v1.6.0+ 2026-08-19 17:14:09 +02:00
init randomize_kstack: Maintain kstack_offset per task 2026-06-19 13:33:41 +02:00
io_uring io_uring/io-wq: re-check IO_WQ_BIT_EXIT for each linked work item 2026-07-24 15:51:21 +02:00
ipc ipc/shm: serialize orphan cleanup with shm_nattch updates 2026-06-19 13:33:38 +02:00
kernel bpf: Preserve pointer state for commuted arithmetic 2026-08-19 17:14:13 +02:00
lib rhashtable: clear stale iter->p on table restart 2026-08-19 17:14:08 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm/huge_memory: unlock i_mmap_rwsem before releasing after-split folios 2026-08-19 17:14:12 +02:00
net tls: don't abort the connection on signal-interrupted sends 2026-08-19 17:14:14 +02:00
samples tracing/events: Fix to check the simple_tsk_fn creation 2026-07-24 15:51:42 +02:00
scripts kconfig: fix potential NULL pointer dereference in conf_askvalue 2026-07-24 15:51:28 +02:00
security keys: make keyring key-chunk byte order agree with keyring_diff_objects() 2026-08-19 17:14:06 +02:00
sound
tools selftests/ftrace: refactor eprobes test to fix argument checks 2026-08-19 17:14:13 +02:00
usr kbuild: hdrcheck: fix cross build with clang 2025-06-27 11:05:22 +01:00
virt KVM: Move kvm_io_bus_get_dev() locking responsibilities to callers 2026-07-24 15:52:02 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-17 15:11:10 +02:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS staging: rtl8712: Remove driver using deprecated API wext 2025-12-07 06:09:36 +09:00
Makefile Linux 5.15.215 2026-08-07 08:07:31 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.