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Filename Latest commit message Latest commit date
Alan Stern 9a39f4626b USB: gadgetfs: Fix race between mounting and unmounting
commit d18dcfe9860e842f394e37ba01ca9440ab2178f4 upstream.

The syzbot fuzzer and Gerald Lee have identified a use-after-free bug
in the gadgetfs driver, involving processes concurrently mounting and
unmounting the gadgetfs filesystem.  In particular, gadgetfs_fill_super()
can race with gadgetfs_kill_sb(), causing the latter to deallocate
the_device while the former is using it.  The output from KASAN says,
in part:

BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:102 [inline]
BUG: KASAN: use-after-free in atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:176 [inline]
BUG: KASAN: use-after-free in __refcount_sub_and_test include/linux/refcount.h:272 [inline]
BUG: KASAN: use-after-free in __refcount_dec_and_test include/linux/refcount.h:315 [inline]
BUG: KASAN: use-after-free in refcount_dec_and_test include/linux/refcount.h:333 [inline]
BUG: KASAN: use-after-free in put_dev drivers/usb/gadget/legacy/inode.c:159 [inline]
BUG: KASAN: use-after-free in gadgetfs_kill_sb+0x33/0x100 drivers/usb/gadget/legacy/inode.c:2086
Write of size 4 at addr ffff8880276d7840 by task syz-executor126/18689

CPU: 0 PID: 18689 Comm: syz-executor126 Not tainted 6.1.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
 <TASK>
...
 atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:176 [inline]
 __refcount_sub_and_test include/linux/refcount.h:272 [inline]
 __refcount_dec_and_test include/linux/refcount.h:315 [inline]
 refcount_dec_and_test include/linux/refcount.h:333 [inline]
 put_dev drivers/usb/gadget/legacy/inode.c:159 [inline]
 gadgetfs_kill_sb+0x33/0x100 drivers/usb/gadget/legacy/inode.c:2086
 deactivate_locked_super+0xa7/0xf0 fs/super.c:332
 vfs_get_super fs/super.c:1190 [inline]
 get_tree_single+0xd0/0x160 fs/super.c:1207
 vfs_get_tree+0x88/0x270 fs/super.c:1531
 vfs_fsconfig_locked fs/fsopen.c:232 [inline]

The simplest solution is to ensure that gadgetfs_fill_super() and
gadgetfs_kill_sb() are serialized by making them both acquire a new
mutex.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-and-tested-by: syzbot+33d7ad66d65044b93f16@syzkaller.appspotmail.com
Reported-and-tested-by: Gerald Lee <sundaywind2004@gmail.com>
Link: https://lore.kernel.org/linux-usb/CAO3qeMVzXDP-JU6v1u5Ags6Q-bb35kg3=C6d04DjzA9ffa5x1g@mail.gmail.com/
Fixes: e5d82a7360 ("vfs: Convert gadgetfs to use the new mount API")
CC: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/Y6XCPXBpn3tmjdCC@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-24 07:18:00 +01:00
arch arm64: cmpxchg_double*: hazard against entire exchange variable 2023-01-18 11:42:05 +01:00
block blk-mq: fix possible memleak when register 'hctx' failed 2023-01-18 11:41:38 +01:00
certs
crypto crypto: tcrypt - Fix multibuffer skcipher speed test mem leak 2023-01-18 11:41:19 +01:00
Documentation docs: Fix the docs build with Sphinx 6.0 2023-01-18 11:42:01 +01:00
drivers USB: gadgetfs: Fix race between mounting and unmounting 2023-01-24 07:18:00 +01:00
fs cifs: do not include page data when checking signature 2023-01-24 07:18:00 +01:00
include usb: acpi: add helper to check port lpm capability using acpi _DSM 2023-01-24 07:17:59 +01:00
init init/Kconfig: fix CC_HAS_ASM_GOTO_TIED_OUTPUT test with dash 2022-12-08 11:22:59 +01:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:23:06 +01:00
kernel prlimit: do_prlimit needs to have a speculation check 2023-01-24 07:17:59 +01:00
lib mm/highmem: Lift memcpy_[to|from]_page to core 2023-01-18 11:41:55 +01:00
LICENSES
mm mm: Always release pages to the buddy allocator in memblock_free_late(). 2023-01-18 11:42:06 +01:00
net net/ethtool/ioctl: return -EOPNOTSUPP if we have no phy stats 2023-01-24 07:17:58 +01:00
samples samples: vfio-mdev: Fix missing pci_disable_device() in mdpy_fb_probe() 2023-01-18 11:41:26 +01:00
scripts scripts/faddr2line: Fix regression in name resolution on ppc64le 2022-12-08 11:23:02 +01:00
security device_cgroup: Roll back to original exceptions after copy failure 2023-01-18 11:41:50 +01:00
sound ALSA: hda/realtek - Turn on power early 2023-01-24 07:17:59 +01:00
tools selftests/bpf: check null propagation only neither reg is PTR_TO_BTF_ID 2023-01-24 07:17:58 +01:00
usr
virt KVM: arm64: vgic: Fix exit condition in scan_its_table() 2022-10-29 10:20:35 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
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COPYING
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Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.229 2023-01-18 11:42:07 +01:00
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.