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Takashi Iwai 8645ac3684 ALSA: rawmidi: Fix racy buffer resize under concurrent accesses
commit c1f6e3c818 upstream.

The rawmidi core allows user to resize the runtime buffer via ioctl,
and this may lead to UAF when performed during concurrent reads or
writes: the read/write functions unlock the runtime lock temporarily
during copying form/to user-space, and that's the race window.

This patch fixes the hole by introducing a reference counter for the
runtime buffer read/write access and returns -EBUSY error when the
resize is performed concurrently against read/write.

Note that the ref count field is a simple integer instead of
refcount_t here, since the all contexts accessing the buffer is
basically protected with a spinlock, hence we need no expensive atomic
ops.  Also, note that this busy check is needed only against read /
write functions, and not in receive/transmit callbacks; the race can
happen only at the spinlock hole mentioned in the above, while the
whole function is protected for receive / transmit callbacks.

Reported-by: butt3rflyh4ck <butterflyhuangxx@gmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/CAFcO6XMWpUVK_yzzCpp8_XP7+=oUpQvuBeCbMffEDkpe8jWrfg@mail.gmail.com
Link: https://lore.kernel.org/r/s5heerw3r5z.wl-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-05-20 08:17:14 +02:00
arch x86/asm: Add instruction suffixes to bitops 2020-05-20 08:17:11 +02:00
block block, bfq: fix use-after-free in bfq_idle_slice_timer_body 2020-04-24 08:00:30 +02:00
certs Replace magic for trusting the secondary keyring with #define 2018-09-09 19:55:54 +02:00
crypto gcc-10: avoid shadowing standard library 'free()' in crypto 2020-05-20 08:17:11 +02:00
Documentation ALSA: doc: Document PC Beep Hidden Register on Realtek ALC256 2020-04-24 08:00:35 +02:00
drivers net: dsa: loop: Add module soft dependency 2020-05-20 08:17:13 +02:00
firmware Fix built-in early-load Intel microcode alignment 2020-01-23 08:20:30 +01:00
fs f2fs: fix to avoid memory leakage in f2fs_listxattr 2020-05-20 08:17:04 +02:00
include ALSA: rawmidi: Fix racy buffer resize under concurrent accesses 2020-05-20 08:17:14 +02:00
init Stop the ad-hoc games with -Wno-maybe-initialized 2020-05-20 08:17:10 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:17:07 +02:00
kernel Stop the ad-hoc games with -Wno-maybe-initialized 2020-05-20 08:17:10 +02:00
lib lib/mpi: Fix building for powerpc with clang 2020-05-10 10:29:01 +02:00
mm shmem: fix possible deadlocks on shmlock_user_lock 2020-05-20 08:17:04 +02:00
net net: tcp: fix rx timestamp behavior for tcp_recvmsg 2020-05-20 08:17:14 +02:00
samples samples/bpf: Don't try to remove user's homedir on clean 2020-02-14 16:32:13 -05:00
scripts scripts/decodecode: fix trapping instruction formatting 2020-05-20 08:17:01 +02:00
security selinux: properly handle multiple messages in selinux_netlink_send() 2020-05-05 19:15:53 +02:00
sound ALSA: rawmidi: Fix racy buffer resize under concurrent accesses 2020-05-20 08:17:14 +02:00
tools objtool: Fix stack offset tracking for indirect CFAs 2020-05-20 08:17:01 +02:00
usr initramfs: restore default compression behavior 2020-04-13 10:34:19 +02:00
virt KVM: arm: vgic: Fix limit condition when writing to GICD_I[CS]ACTIVER 2020-05-20 08:16:58 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: rpm-pkg: keep spec file until make mrproper 2018-02-13 10:19:46 +01:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS MAINTAINERS: Update drm/i915 bug filing URL 2020-02-28 16:36:12 +01:00
Makefile gcc-10: disable 'restrict' warning for now 2020-05-20 08:17:11 +02:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.