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Filename Latest commit message Latest commit date
Miklos Szeredi 34468b2e39 fuse: don't truncate cached, mutated symlink
[ Upstream commit b4c173dfbb6c78568578ff18f9e8822d7bd0e31b ]

Fuse allows the value of a symlink to change and this property is exploited
by some filesystems (e.g. CVMFS).

It has been observed, that sometimes after changing the symlink contents,
the value is truncated to the old size.

This is caused by fuse_getattr() racing with fuse_reverse_inval_inode().
fuse_reverse_inval_inode() updates the fuse_inode's attr_version, which
results in fuse_change_attributes() exiting before updating the cached
attributes

This is okay, as the cached attributes remain invalid and the next call to
fuse_change_attributes() will likely update the inode with the correct
values.

The reason this causes problems is that cached symlinks will be
returned through page_get_link(), which truncates the symlink to
inode->i_size.  This is correct for filesystems that don't mutate
symlinks, but in this case it causes bad behavior.

The solution is to just remove this truncation.  This can cause a
regression in a filesystem that relies on supplying a symlink larger than
the file size, but this is unlikely.  If that happens we'd need to make
this behavior conditional.

Reported-by: Laura Promberger <laura.promberger@cern.ch>
Tested-by: Sam Lewis <samclewis@google.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Link: https://lore.kernel.org/r/20250220100258.793363-1-mszeredi@redhat.com
Reviewed-by: Bernd Schubert <bschubert@ddn.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-04-10 14:29:36 +02:00
arch clockevents/drivers/i8253: Fix stop sequence for timer 0 2025-04-10 14:29:34 +02:00
block partitions: mac: fix handling of bogus partition table 2025-03-13 12:43:16 +01:00
certs
crypto crypto: testmgr - some more fixes to RSA test vectors 2025-03-13 12:43:21 +01:00
Documentation sched/isolation: Prevent boot crash when the boot CPU is nohz_full 2025-04-10 14:29:35 +02:00
drivers nvme: only allow entering LIVE from CONNECTING state 2025-04-10 14:29:36 +02:00
fs fuse: don't truncate cached, mutated symlink 2025-04-10 14:29:36 +02:00
include fuse: don't truncate cached, mutated symlink 2025-04-10 14:29:36 +02:00
init initramfs: avoid filename buffer overrun 2024-12-14 19:44:21 +01:00
ipc
kernel hrtimers: Mark is_migration_base() with __always_inline 2025-04-10 14:29:36 +02:00
lib lib: string_helpers: silence snprintf() output truncation warning 2024-12-14 19:44:39 +01:00
LICENSES
mm mm/page_alloc: fix uninitialized variable 2025-03-13 12:43:28 +01:00
net sctp: Fix undefined behavior in left shift operation 2025-04-10 14:29:36 +02:00
samples samples/bpf: Fix a resource leak 2024-12-14 19:44:50 +01:00
scripts kbuild: Move -Wenum-enum-conversion to W=2 2025-03-13 12:43:09 +01:00
security ima: Fix use-after-free on a dentry's dname.name 2025-03-13 12:43:19 +01:00
sound ASoC: rsnd: don't indicate warning on rsnd_kctrl_accept_runtime() 2025-04-10 14:29:36 +02:00
tools perf bench: Fix undefined behavior in cmpworker() 2025-03-13 12:43:08 +01:00
usr
virt KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status 2024-12-19 18:05:04 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore Remove *.orig pattern from .gitignore 2024-11-08 16:20:33 +01:00
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.291 2025-03-13 12:43:33 +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.