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Alan Stern ff33299ec8 USB: core: Fix race by not overwriting udev->descriptor in hub_port_init() 
Syzbot reported an out-of-bounds read in sysfs.c:read_descriptors():

BUG: KASAN: slab-out-of-bounds in read_descriptors+0x263/0x280 drivers/usb/core/sysfs.c:883
Read of size 8 at addr ffff88801e78b8c8 by task udevd/5011

CPU: 0 PID: 5011 Comm: udevd Not tainted 6.4.0-rc6-syzkaller-00195-g40f71e7cd3c6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
 print_address_description.constprop.0+0x2c/0x3c0 mm/kasan/report.c:351
 print_report mm/kasan/report.c:462 [inline]
 kasan_report+0x11c/0x130 mm/kasan/report.c:572
 read_descriptors+0x263/0x280 drivers/usb/core/sysfs.c:883
...
Allocated by task 758:
...
 __do_kmalloc_node mm/slab_common.c:966 [inline]
 __kmalloc+0x5e/0x190 mm/slab_common.c:979
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:680 [inline]
 usb_get_configuration+0x1f7/0x5170 drivers/usb/core/config.c:887
 usb_enumerate_device drivers/usb/core/hub.c:2407 [inline]
 usb_new_device+0x12b0/0x19d0 drivers/usb/core/hub.c:2545

As analyzed by Khazhy Kumykov, the cause of this bug is a race between
read_descriptors() and hub_port_init(): The first routine uses a field
in udev->descriptor, not expecting it to change, while the second
overwrites it.

Prior to commit 45bf39f8df ("USB: core: Don't hold device lock while
reading the "descriptors" sysfs file") this race couldn't occur,
because the routines were mutually exclusive thanks to the device
locking.  Removing that locking from read_descriptors() exposed it to
the race.

The best way to fix the bug is to keep hub_port_init() from changing
udev->descriptor once udev has been initialized and registered.
Drivers expect the descriptors stored in the kernel to be immutable;
we should not undermine this expectation.  In fact, this change should
have been made long ago.

So now hub_port_init() will take an additional argument, specifying a
buffer in which to store the device descriptor it reads.  (If udev has
not yet been initialized, the buffer pointer will be NULL and then
hub_port_init() will store the device descriptor in udev as before.)
This eliminates the data race responsible for the out-of-bounds read.

The changes to hub_port_init() appear more extensive than they really
are, because of indentation changes resulting from an attempt to avoid
writing to other parts of the usb_device structure after it has been
initialized.  Similar changes should be made to the code that reads
the BOS descriptor, but that can be handled in a separate patch later
on.  This patch is sufficient to fix the bug found by syzbot.

Reported-and-tested-by: syzbot+18996170f8096c6174d0@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-usb/000000000000c0ffe505fe86c9ca@google.com/#r
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: Khazhy Kumykov <khazhy@google.com>
Fixes: 45bf39f8df ("USB: core: Don't hold device lock while reading the "descriptors" sysfs file")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/b958b47a-9a46-4c22-a9f9-e42e42c31251@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2023-08-08 10:45:32 +02:00
Documentation dt-bindings: usb: ci-hdrc-usb2: Fix clocks/clock-names maxItems 2023-08-04 14:47:11 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
arch usb: dwc3: dwc3-octeon: Convert to glue driver 2023-08-04 14:52:15 +02:00
block block-6.5-2023-07-21 2023-07-22 11:05:15 -07:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto crypto: algif_hash - Fix race between MORE and non-MORE sends 2023-07-08 22:48:42 +10:00
drivers USB: core: Fix race by not overwriting udev->descriptor in hub_port_init() 2023-08-08 10:45:32 +02:00
fs four small client fixes 2023-07-29 20:49:13 -07:00
include Merge 6.5-rc4 into usb-next 2023-07-31 09:36:55 +02:00
init Kbuild updates for v6.5 2023-07-01 09:24:31 -07:00
io_uring io_uring-6.5-2023-07-28 2023-07-28 10:19:44 -07:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel Probe fixes for 6.5-rc3: 2023-07-30 11:27:22 -07:00
lib Char driver and Documentation fixes for 6.5-rc4 2023-07-30 11:44:00 -07:00
mm 11 hotfixes. Five are cc:stable and the remainder address post-6.4 issues 2023-07-28 17:19:52 -07:00
net A patch to reduce the potential for erroneous RBD exclusive lock 2023-07-28 10:47:24 -07:00
rust rust: error: `impl Debug` for `Error` with `errname()` integration 2023-06-13 01:24:42 +02:00
samples arm64: ftrace: Add direct call trampoline samples support 2023-07-10 17:51:54 -04:00
scripts x86: 2023-07-30 11:19:08 -07:00
security security: keys: perform capable check only on privileged operations 2023-07-28 18:07:41 +00:00
sound ASoC: Fixes for v6.5 2023-07-27 14:54:23 +02:00
tools Probe fixes for 6.5-rc3: 2023-07-30 11:27:22 -07:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Grab a reference to KVM for VM and vCPU stats file descriptors 2023-07-29 11:05:28 -04:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Revert ".gitignore: ignore *.cover and *.mbx" 2023-07-04 15:05:12 -07:00
.mailmap mailmap: update remaining active codeaurora.org email addresses 2023-07-27 13:07:05 -07:00
.rustfmt.toml rust: add `.rustfmt.toml` 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS - Address -Wmissing-prototype warnings 2023-06-26 16:43:54 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS USB fixes for 6.5-rc4 2023-07-30 11:57:51 -07:00
Makefile Linux 6.5-rc4 2023-07-30 13:23:47 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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.