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Shyam Prasad N f655467a99 cifs: open files should not hold ref on superblock
[ Upstream commit 340cea84f6 ]

Today whenever we deal with a file, in addition to holding
a reference on the dentry, we also get a reference on the
superblock. This happens in two cases:
1. when a new cinode is allocated
2. when an oplock break is being processed

The reasoning for holding the superblock ref was to make sure
that when umount happens, if there are users of inodes and
dentries, it does not try to clean them up and wait for the
last ref to superblock to be dropped by last of such users.

But the side effect of doing that is that umount silently drops
a ref on the superblock and we could have deferred closes and
lease breaks still holding these refs.

Ideally, we should ensure that all of these users of inodes and
dentries are cleaned up at the time of umount, which is what this
code is doing.

This code change allows these code paths to use a ref on the
dentry (and hence the inode). That way, umount is
ensured to clean up SMB client resources when it's the last
ref on the superblock (For ex: when same objects are shared).

The code change also moves the call to close all the files in
deferred close list to the umount code path. It also waits for
oplock_break workers to be flushed before calling
kill_anon_super (which eventually frees up those objects).

Fixes: 24261fc23d ("cifs: delay super block destruction until all cifsFileInfo objects are gone")
Fixes: 705c79101c ("smb: client: fix use-after-free in cifs_oplock_break")
Cc: <stable@vger.kernel.org>
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
[ replaced kmalloc_obj() with kmalloc(sizeof(...)) ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2026-03-25 11:10:32 +01:00
arch LoongArch: Check return values for set_memory_{rw,rox} 2026-03-25 11:10:32 +01:00
block block: use trylock to avoid lockdep circular dependency in sysfs 2026-03-12 07:09:59 -04:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: authencesn - reject too-short AAD (assoclen<8) to match ESP/ESN spec 2026-01-30 10:32:12 +01:00
Documentation KVM: x86: Introduce KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM 2026-03-19 16:08:24 +01:00
drivers crypto: atmel-sha204a - Fix OOM ->tfm_count leak 2026-03-25 11:10:32 +01:00
fs
include io_uring: ensure ctx->rings is stable for task work flags manipulation 2026-03-19 16:08:51 +01:00
init printk changes for 6.18 2025-10-04 11:13:11 -07:00
io_uring io_uring/eventfd: use ctx->rings_rcu for flags checking 2026-03-19 16:08:51 +01:00
ipc ipc: don't audit capability check in ipc_permissions() 2026-02-26 14:59:19 -08:00
kernel crash_dump: don't log dm-crypt key bytes in read_key_from_user_keying 2026-03-25 11:10:30 +01:00
lib lib/crypto: tests: Depend on library options rather than selecting them 2026-03-19 16:08:50 +01:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm mm/huge_memory: fix early failure try_to_migrate() when split huge pmd for shared THP 2026-03-25 11:10:30 +01:00
net Bluetooth: L2CAP: Validate L2CAP_INFO_RSP payload length before access 2026-03-25 11:10:31 +01:00
rust rust: str: make NullTerminatedFormatter public 2026-03-19 16:08:24 +01:00
samples samples/ftrace: Adjust LoongArch register restore order in direct calls 2026-01-08 10:17:11 +01:00
scripts kbuild: rpm-pkg: Disable automatic requires for manual debuginfo package 2026-03-04 07:21:32 -05:00
security apparmor: fix race between freeing data and fs accessing it 2026-03-13 17:23:30 +01:00
sound ALSA: usb-audio: Improve Focusrite sample rate filtering 2026-03-19 16:08:31 +01:00
tools selftests/hid: fix compilation when bpf_wq and hid_device are not exported 2026-03-25 11:10:30 +01:00
usr gen_init_cpio: Ignore fsync() returning EINVAL on pipes 2025-10-07 09:53:05 -07:00
virt KVM: Don't clobber irqfd routing type when deassigning irqfd 2026-02-11 13:41:44 +01:00
.clang-format memblock: drop for_each_free_mem_pfn_range_in_zone_from() 2025-09-14 08:49:03 +03:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore .gitignore: ignore compile_commands.json globally 2025-08-12 15:53:55 -07:00
.mailmap 8 hotfixes. 4 are cc:stable, 7 are against mm/. 2025-11-26 12:38:05 -08:00
.pylintrc tools: docs: parse-headers.py: move it from sphinx dir 2025-08-29 15:54:42 -06:00
.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 MAINTAINERS: mark ISDN subsystem as orphan 2025-10-27 17:49:45 -07:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS soc: fixes for 6.18, part 4 2025-11-28 09:57:31 -08:00
Makefile Linux 6.18.19 2026-03-19 16:08:51 +01:00
README README: Fix spelling 2024-03-18 03:36:32 -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 reStructuredText 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.