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Jeff Layton ed9ab7346e nfsd: move init of percpu reply_cache_stats counters back to nfsd_init_net 
Commit f5f9d4a314 ("nfsd: move reply cache initialization into nfsd
startup") moved the initialization of the reply cache into nfsd startup,
but didn't account for the stats counters, which can be accessed before
nfsd is ever started. The result can be a NULL pointer dereference when
someone accesses /proc/fs/nfsd/reply_cache_stats while nfsd is still
shut down.

This is a regression and a user-triggerable oops in the right situation:

- non-x86_64 arch
- /proc/fs/nfsd is mounted in the namespace
- nfsd is not started in the namespace
- unprivileged user calls "cat /proc/fs/nfsd/reply_cache_stats"

Although this is easy to trigger on some arches (like aarch64), on
x86_64, calling this_cpu_ptr(NULL) evidently returns a pointer to the
fixed_percpu_data. That struct looks just enough like a newly
initialized percpu var to allow nfsd_reply_cache_stats_show to access
it without Oopsing.

Move the initialization of the per-net+per-cpu reply-cache counters
back into nfsd_init_net, while leaving the rest of the reply cache
allocations to be done at nfsd startup time.

Kudos to Eirik who did most of the legwork to track this down.

Cc: stable@vger.kernel.org # v6.3+
Fixes: f5f9d4a314 ("nfsd: move reply cache initialization into nfsd startup")
Reported-and-tested-by: Eirik Fuller <efuller@redhat.com>
Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2215429
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
History 2023-06-18 12:02:40 -04:00
arch ARM: 2023-06-04 07:16:53 -04:00
block block: fix revalidate performance regression 2023-05-29 08:40:32 -06:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto This push fixes the following problems: 2023-05-07 10:57:14 -07:00
Documentation Char/Misc driver fixes for 6.4-rc5 2023-06-04 08:32:30 -04:00
drivers - Fix open firmware quirks validation so that they don't get applied 2023-06-04 11:57:38 -04:00
fs nfsd: move init of percpu reply_cache_stats counters back to nfsd_init_net 2023-06-18 12:02:40 -04:00
include svcrdma: trace cc_release calls 2023-06-17 13:18:06 -04:00
init Objtool changes for v6.4: 2023-04-28 14:02:54 -07:00
io_uring io_uring: undeprecate epoll_ctl support 2023-05-26 20:22:41 -06:00
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 Probes fixes for 6.4-rc4: 2023-06-03 08:23:16 -04:00
lib test_firmware: fix the memory leak of the allocated firmware buffer 2023-05-31 20:31:07 +01:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: page_table_check: Ensure user pages are not slab pages 2023-05-29 16:14:28 +01:00
net SUNRPC: Address RCU warning in net/sunrpc/svc.c 2023-06-17 13:18:07 -04:00
rust Rust changes for v6.4 2023-04-30 11:20:22 -07:00
samples samples/bpf: Drop unnecessary fallthrough 2023-05-16 19:44:05 +02:00
scripts Locking changes in v6.4: 2023-05-05 12:56:55 -07:00
security selinux: don't use make's grouped targets feature yet 2023-06-01 13:56:13 -04:00
sound ALSA: hda/realtek: Enable headset onLenovo M70/M90 2023-05-24 14:18:59 +02:00
tools ARM: 2023-06-04 07:16:53 -04:00
usr initramfs: Check negative timestamp to prevent broken cpio archive 2023-04-16 17:37:01 +09:00
virt KVM: Fix vcpu_array[0] races 2023-05-19 13:56:26 -04:00
.clang-format cxl for v6.4 2023-04-30 11:51:51 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore linux-kselftest-kunit-6.4-rc1 2023-04-24 12:31:32 -07:00
.mailmap mailmap: Add Bruce Fields' latest e-mail addresses 2023-06-12 12:16:35 -04:00
.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: sctp: move Neil to CREDITS 2023-05-12 08:51:32 +01:00
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 NFSD: Add "official" reviewers for this subsystem 2023-06-12 12:16:35 -04:00
Makefile Linux 6.4-rc5 2023-06-04 14:04:27 -04:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.