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Nalivayko Sergey 94797b84cb net/9p: fix double req put in p9_fd_cancelled 
commit 674b56aa57 upstream.

Syzkaller reports a KASAN issue as below:

general protection fault, probably for non-canonical address 0xfbd59c0000000021: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: maybe wild-memory-access in range [0xdead000000000108-0xdead00000000010f]
CPU: 0 PID: 5083 Comm: syz-executor.2 Not tainted 6.1.134-syzkaller-00037-g855bd1d7d838 #0
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
RIP: 0010:__list_del include/linux/list.h:114 [inline]
RIP: 0010:__list_del_entry include/linux/list.h:137 [inline]
RIP: 0010:list_del include/linux/list.h:148 [inline]
RIP: 0010:p9_fd_cancelled+0xe9/0x200 net/9p/trans_fd.c:734

Call Trace:
 <TASK>
 p9_client_flush+0x351/0x440 net/9p/client.c:614
 p9_client_rpc+0xb6b/0xc70 net/9p/client.c:734
 p9_client_version net/9p/client.c:920 [inline]
 p9_client_create+0xb51/0x1240 net/9p/client.c:1027
 v9fs_session_init+0x1f0/0x18f0 fs/9p/v9fs.c:408
 v9fs_mount+0xba/0xcb0 fs/9p/vfs_super.c:126
 legacy_get_tree+0x108/0x220 fs/fs_context.c:632
 vfs_get_tree+0x8e/0x300 fs/super.c:1573
 do_new_mount fs/namespace.c:3056 [inline]
 path_mount+0x6a6/0x1e90 fs/namespace.c:3386
 do_mount fs/namespace.c:3399 [inline]
 __do_sys_mount fs/namespace.c:3607 [inline]
 __se_sys_mount fs/namespace.c:3584 [inline]
 __x64_sys_mount+0x283/0x300 fs/namespace.c:3584
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x6e/0xd8

This happens because of a race condition between:

- The 9p client sending an invalid flush request and later cleaning it up;
- The 9p client in p9_read_work() canceled all pending requests.

      Thread 1                              Thread 2
    ...
    p9_client_create()
    ...
    p9_fd_create()
    ...
    p9_conn_create()
    ...
    // start Thread 2
    INIT_WORK(&m->rq, p9_read_work);
                                        p9_read_work()
    ...
    p9_client_rpc()
    ...
                                        ...
                                        p9_conn_cancel()
                                        ...
                                        spin_lock(&m->req_lock);
    ...
    p9_fd_cancelled()
    ...
                                        ...
                                        spin_unlock(&m->req_lock);
                                        // status rewrite
                                        p9_client_cb(m->client, req, REQ_STATUS_ERROR)
                                        // first remove
                                        list_del(&req->req_list);
                                        ...

    spin_lock(&m->req_lock)
    ...
    // second remove
    list_del(&req->req_list);
    spin_unlock(&m->req_lock)
  ...

Commit 74d6a5d566 ("9p/trans_fd: Fix concurrency del of req_list in
p9_fd_cancelled/p9_read_work") fixes a concurrency issue in the 9p filesystem
client where the req_list could be deleted simultaneously by both
p9_read_work and p9_fd_cancelled functions, but for the case where req->status
equals REQ_STATUS_RCVD.

Update the check for req->status in p9_fd_cancelled to skip processing not
just received requests, but anything that is not SENT, as whatever
changed the state from SENT also removed the request from its list.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Fixes: afd8d65411 ("9P: Add cancelled() to the transport functions.")
Cc: stable@vger.kernel.org
Signed-off-by: Nalivayko Sergey <Sergey.Nalivayko@kaspersky.com>
Message-ID: <20250715154815.3501030-1-Sergey.Nalivayko@kaspersky.com>
[updated the check from status == RECV || status == ERROR to status != SENT]
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-10-12 13:01:57 +02:00
arch ARM fixes for 6.17 2025-09-28 13:24:43 -07:00
block blk-mq: fix blk_mq_tags double free while nr_requests grown 2025-10-06 11:20:04 +02:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: rng - Ensure set_ent is always present 2025-10-12 13:01:57 +02:00
Documentation i2c-for-6.17-rc8 2025-09-28 13:19:23 -07:00
drivers driver core: faux: Set power.no_pm for faux devices 2025-10-12 13:01:57 +02:00
fs 7 hotfixes. 4 are cc:stable and the remainder address post-6.16 issues or 2025-09-28 09:32:00 -07:00
include driver core/PM: Set power.no_callbacks along with power.no_pm 2025-10-12 13:01:57 +02:00
init kbuild: Disable CC_HAS_ASM_GOTO_OUTPUT on clang < 17 2025-09-24 09:29:15 +02:00
io_uring io_uring-6.17-20250919 2025-09-19 12:10:49 -07:00
ipc vfs-6.17-rc1.mmap_prepare 2025-07-28 13:43:25 -07:00
kernel tracing fixes for v6.17 2025-09-28 10:26:35 -07:00
lib hardening fixes for v6.17-rc4 2025-08-31 08:56:45 -07:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm mm: swap: check for stable address space before operating on the VMA 2025-10-06 11:20:05 +02:00
net net/9p: fix double req put in p9_fd_cancelled 2025-10-12 13:01:57 +02:00
rust rust: pci: fix incorrect platform reference in PCI driver unbind doc comment 2025-10-12 13:01:55 +02:00
samples 15 hotfixes. 11 are cc:stable and the remainder address post-6.16 issues 2025-09-17 21:34:26 -07:00
scripts gcc-plugins: Remove TODO_verify_il for GCC >= 16 2025-10-06 11:20:04 +02:00
security + Features 2025-08-04 08:17:28 -07:00
sound ASoC: qcom: audioreach: fix potential null pointer dereference 2025-10-06 11:20:06 +02:00
tools Two fixes for rtla in v6.17: 2025-09-27 09:50:46 -07:00
usr usr/include: openrisc: don't HDRTEST bpf_perf_event.h 2025-05-12 15:03:17 +09:00
virt Merge tag 'kvm-x86-no_assignment-6.17' of https://github.com/kvm-x86/linux into HEAD 2025-07-29 08:36:42 -04:00
.clang-format Linux 6.15-rc5 2025-05-06 16:39:25 +10:00
.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: allow .pylintrc to be tracked 2025-07-02 17:10:04 -06:00
.mailmap 7 hotfixes. 4 are cc:stable and the remainder address post-6.16 issues or 2025-09-28 09:32:00 -07:00
.pylintrc docs: add a .pylintrc file with sys path for docs scripts 2025-04-09 12:10:33 -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: retire Boris from TLS maintainers 2025-08-26 17:36:01 -07:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS i2c-for-6.17-rc8 2025-09-28 13:19:23 -07:00
Makefile Linux 6.17.1 2025-10-06 11:20:06 +02:00
README README: Fix spelling 2024-03-18 03:36:32 -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 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.