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Andreas Gruenbacher f66af88e33 gfs2: Stop using gfs2_make_fs_ro for withdraw
[   81.372851][ T5532] CPU: 1 PID: 5532 Comm: syz-executor.0 Not tainted 6.2.0-rc1-syzkaller-dirty #0
[   81.382080][ T5532] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
[   81.392343][ T5532] Call Trace:
[   81.395654][ T5532]  <TASK>
[   81.398603][ T5532]  dump_stack_lvl+0x1b1/0x290
[   81.418421][ T5532]  gfs2_assert_warn_i+0x19a/0x2e0
[   81.423480][ T5532]  gfs2_quota_cleanup+0x4c6/0x6b0
[   81.428611][ T5532]  gfs2_make_fs_ro+0x517/0x610
[   81.457802][ T5532]  gfs2_withdraw+0x609/0x1540
[   81.481452][ T5532]  gfs2_inode_refresh+0xb2d/0xf60
[   81.506658][ T5532]  gfs2_instantiate+0x15e/0x220
[   81.511504][ T5532]  gfs2_glock_wait+0x1d9/0x2a0
[   81.516352][ T5532]  do_sync+0x485/0xc80
[   81.554943][ T5532]  gfs2_quota_sync+0x3da/0x8b0
[   81.559738][ T5532]  gfs2_sync_fs+0x49/0xb0
[   81.564063][ T5532]  sync_filesystem+0xe8/0x220
[   81.568740][ T5532]  generic_shutdown_super+0x6b/0x310
[   81.574112][ T5532]  kill_block_super+0x79/0xd0
[   81.578779][ T5532]  deactivate_locked_super+0xa7/0xf0
[   81.584064][ T5532]  cleanup_mnt+0x494/0x520
[   81.593753][ T5532]  task_work_run+0x243/0x300
[   81.608837][ T5532]  exit_to_user_mode_loop+0x124/0x150
[   81.614232][ T5532]  exit_to_user_mode_prepare+0xb2/0x140
[   81.619820][ T5532]  syscall_exit_to_user_mode+0x26/0x60
[   81.625287][ T5532]  do_syscall_64+0x49/0xb0
[   81.629710][ T5532]  entry_SYSCALL_64_after_hwframe+0x63/0xcd

In this backtrace, gfs2_quota_sync() takes quota data references and
then calls do_sync().  Function do_sync() encounters filesystem
corruption and withdraws the filesystem, which (among other things) calls
gfs2_quota_cleanup().  Function gfs2_quota_cleanup() wrongly assumes
that nobody is holding any quota data references anymore, and destroys
all quota data objects.  When gfs2_quota_sync() then resumes and
dereferences the quota data objects it is holding, those objects are no
longer there.

Function gfs2_quota_cleanup() deals with resource deallocation and can
easily be delayed until gfs2_put_super() in the case of a filesystem
withdraw.  In fact, most of the other work gfs2_make_fs_ro() does is
unnecessary during a withdraw as well, so change signal_our_withdraw()
to skip gfs2_make_fs_ro() and perform the necessary steps directly
instead.

Thanks to Edward Adam Davis <eadavis@sina.com> for the initial patches.

Link: https://lore.kernel.org/all/0000000000002b5e2405f14e860f@google.com
Reported-by: syzbot+3f6a670108ce43356017@syzkaller.appspotmail.com
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2023-09-05 15:58:17 +02:00
arch Mitigate Gather Data Sampling issue 2023-08-07 17:03:54 -07:00
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
Documentation gfs2: Remove LM_FLAG_PRIORITY flag 2023-09-05 15:58:16 +02:00
drivers xen: XSA-432 security patches for v6.5 2023-08-07 17:25:19 -07:00
fs gfs2: Stop using gfs2_make_fs_ro for withdraw 2023-09-05 15:58:17 +02:00
include Add a mitigation for the speculative RAS (Return Address Stack) overflow 2023-08-07 16:35:44 -07:00
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 workqueue: Fixes for v6.5-rc5 2023-08-07 13:07:12 -07:00
lib workqueue: Fixes for v6.5-rc5 2023-08-07 13:07:12 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm 11 hotfixes. Five are cc:stable and the remainder address post-6.4 issues 2023-07-28 17:19:52 -07:00
net Two patches to improve RBD exclusive lock interaction with 2023-08-04 11:29:38 -07:00
rust rust: fix bindgen build error with UBSAN_BOUNDS_STRICT 2023-08-04 17:10:50 +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 sysctl: set variable key_sysctls storage-class-specifier to static 2023-08-07 17:55:54 +00:00
sound ASoC: Fixes for v6.5 2023-07-27 14:54:23 +02:00
tools Add a mitigation for the speculative RAS (Return Address Stack) overflow 2023-08-07 16:35:44 -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
.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 Raw NAND fixes: 2023-08-04 12:01:26 -07:00
Makefile Linux 6.5-rc5 2023-08-06 15:07:51 -07:00
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.