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Brian Foster e3b83d87c9 ext4: fix racy may inline data check in dio write
commit ce56d21355 upstream.

syzbot reports that the following warning from ext4_iomap_begin()
triggers as of the commit referenced below:

        if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
                return -ERANGE;

This occurs during a dio write, which is never expected to encounter
an inode with inline data. To enforce this behavior,
ext4_dio_write_iter() checks the current inline state of the inode
and clears the MAY_INLINE_DATA state flag to either fall back to
buffered writes, or enforce that any other writers in progress on
the inode are not allowed to create inline data.

The problem is that the check for existing inline data and the state
flag can span a lock cycle. For example, if the ilock is originally
locked shared and subsequently upgraded to exclusive, another writer
may have reacquired the lock and created inline data before the dio
write task acquires the lock and proceeds.

The commit referenced below loosens the lock requirements to allow
some forms of unaligned dio writes to occur under shared lock, but
AFAICT the inline data check was technically already racy for any
dio write that would have involved a lock cycle. Regardless, lift
clearing of the state bit to the same lock critical section that
checks for preexisting inline data on the inode to close the race.

Cc: stable@kernel.org
Reported-by: syzbot+307da6ca5cb0d01d581a@syzkaller.appspotmail.com
Fixes: 310ee0902b ("ext4: allow concurrent unaligned dio overwrites")
Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20231002185020.531537-1-bfoster@redhat.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-11-28 17:15:17 +00:00
Documentation torture: Add lock_torture writer_fifo module parameter 2023-11-28 17:15:09 +00:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
arch riscv: kprobes: allow writing to x0 2023-11-28 17:15:15 +00:00
block blk-mq: make sure active queue usage is held for bio_integrity_prep() 2023-11-28 17:14:55 +00:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto crypto: pcrypt - Fix hungtask for PADATA_RESET 2023-11-28 17:14:46 +00:00
drivers Revert "net: r8169: Disable multicast filter for RTL8168H and RTL8107E" 2023-11-28 17:15:16 +00:00
fs ext4: fix racy may inline data check in dio write 2023-11-28 17:15:17 +00:00
include net: ethtool: Fix documentation of ethtool_sprintf() 2023-11-28 17:15:12 +00:00
init proc: sysctl: prevent aliased sysctls from getting passed to init 2023-11-28 17:15:00 +00:00
io_uring io_uring/fdinfo: remove need for sqpoll lock for thread/pid retrieval 2023-11-28 17:14:56 +00:00
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 rcutorture: Fix stuttering races and other issues 2023-11-28 17:15:10 +00:00
lib lib/generic-radix-tree.c: Don't overflow in peek() 2023-11-28 17:14:40 +00:00
mm mm: kmem: drop __GFP_NOFAIL when allocating objcg vectors 2023-11-28 17:15:15 +00:00
net mptcp: fix setsockopt(IP_TOS) subflow locking 2023-11-28 17:15:15 +00:00
rust rust: types: make `Opaque` be `!Unpin` 2023-11-08 14:09:04 +01:00
samples samples/bpf: syscall_tp_user: Fix array out-of-bound access 2023-11-28 17:14:52 +00:00
scripts randstruct: Fix gcc-plugin performance mode to stay in group 2023-11-28 17:14:58 +00:00
security ima: detect changes to the backing overlay file 2023-11-28 17:15:06 +00:00
sound ALSA: hda/realtek: Add quirks for HP Laptops 2023-11-28 17:15:12 +00:00
tools selftests: mptcp: fix fastclose with csum failure 2023-11-28 17:15:15 +00:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() 2023-09-13 09:53:29 +02:00
.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: add entries for Simon Horman 2023-08-16 09:53:10 +01:00
.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 sound fixes for 6.5 2023-08-25 08:48:14 -07:00
Makefile Linux 6.5.12 2023-11-20 11:57:26 +01:00
README

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.