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Stefano Stabellini 59e7707492 9p/xen: protect xen_9pfs_front_free against concurrent calls
[ Upstream commit ce8ded2e61 ]

The xenwatch thread can race with other back-end change notifications
and call xen_9pfs_front_free() twice, hitting the observed general
protection fault due to a double-free. Guard the teardown path so only
one caller can release the front-end state at a time, preventing the
crash.

This is a fix for the following double-free:

[   27.052347] Oops: general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b6b: 0000 [#1] SMP DEBUG_PAGEALLOC NOPTI
[   27.052357] CPU: 0 UID: 0 PID: 32 Comm: xenwatch Not tainted 6.18.0-02087-g51ab33fc0a8b-dirty #60 PREEMPT(none)
[   27.052363] RIP: e030:xen_9pfs_front_free+0x1d/0x150
[   27.052368] Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 41 55 41 54 55 48 89 fd 48 c7 c7 48 d0 92 85 53 e8 cb cb 05 00 48 8b 45 08 48 8b 55 00 <48> 3b 28 0f 85 f9 28 35 fe 48 3b 6a 08 0f 85 ef 28 35 fe 48 89 42
[   27.052377] RSP: e02b:ffffc9004016fdd0 EFLAGS: 00010246
[   27.052381] RAX: 6b6b6b6b6b6b6b6b RBX: ffff88800d66e400 RCX: 0000000000000000
[   27.052385] RDX: 6b6b6b6b6b6b6b6b RSI: 0000000000000000 RDI: 0000000000000000
[   27.052389] RBP: ffff88800a887040 R08: 0000000000000000 R09: 0000000000000000
[   27.052393] R10: 0000000000000000 R11: 0000000000000000 R12: ffff888009e46b68
[   27.052397] R13: 0000000000000200 R14: 0000000000000000 R15: ffff88800a887040
[   27.052404] FS:  0000000000000000(0000) GS:ffff88808ca57000(0000) knlGS:0000000000000000
[   27.052408] CS:  e030 DS: 0000 ES: 0000 CR0: 0000000080050033
[   27.052412] CR2: 00007f9714004360 CR3: 0000000004834000 CR4: 0000000000050660
[   27.052418] Call Trace:
[   27.052420]  <TASK>
[   27.052422]  xen_9pfs_front_changed+0x5d5/0x720
[   27.052426]  ? xenbus_otherend_changed+0x72/0x140
[   27.052430]  ? __pfx_xenwatch_thread+0x10/0x10
[   27.052434]  xenwatch_thread+0x94/0x1c0
[   27.052438]  ? __pfx_autoremove_wake_function+0x10/0x10
[   27.052442]  kthread+0xf8/0x240
[   27.052445]  ? __pfx_kthread+0x10/0x10
[   27.052449]  ? __pfx_kthread+0x10/0x10
[   27.052452]  ret_from_fork+0x16b/0x1a0
[   27.052456]  ? __pfx_kthread+0x10/0x10
[   27.052459]  ret_from_fork_asm+0x1a/0x30
[   27.052463]  </TASK>
[   27.052465] Modules linked in:
[   27.052471] ---[ end trace 0000000000000000 ]---

Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com>
Message-ID: <20260129230348.2390470-1-stefano.stabellini@amd.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2026-03-04 07:20:31 -05:00
arch m68k: nommu: fix memmove() with differently aligned src and dest for 68000 2026-03-04 07:20:31 -05:00
block block: decouple secure erase size limit from discard size limit 2026-03-04 07:19:38 -05:00
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 hwmon: (nct6683) Add customer ID for ASRock Z590 Taichi 2026-03-04 07:20:06 -05:00
drivers HID: i2c-hid: Add FocalTech FT8112 2026-03-04 07:20:31 -05:00
fs ext4: propagate flags to convert_initialized_extent() 2026-03-04 07:20:21 -05:00
include PCI/bwctrl: Disable BW controller on Intel P45 using a quirk 2026-03-04 07:20:27 -05:00
init printk changes for 6.18 2025-10-04 11:13:11 -07:00
io_uring io_uring/timeout: annotate data race in io_flush_timeouts() 2026-03-04 07:19:36 -05:00
ipc ipc: don't audit capability check in ipc_permissions() 2026-02-26 14:59:19 -08:00
kernel tracing: Fix false sharing in hwlat get_sample() 2026-03-04 07:20:29 -05:00
lib objpool: fix the overestimation of object pooling metadata size 2026-02-26 14:59:36 -08:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm mm/slab: fix false lockdep warning in __kfree_rcu_sheaf() 2026-02-26 14:59:14 -08:00
net 9p/xen: protect xen_9pfs_front_free against concurrent calls 2026-03-04 07:20:31 -05:00
rust rust: cpufreq: always inline functions using build_assert with arguments 2026-03-04 07:19:37 -05:00
samples samples/ftrace: Adjust LoongArch register restore order in direct calls 2026-01-08 10:17:11 +01:00
scripts modpost: Amend ppc64 save/restfpr symnames for -Os build 2026-03-04 07:20:07 -05:00
security apparmor: fix aa_label to return state from compount and component match 2026-02-26 14:59:42 -08:00
sound ALSA: usb-audio: Add iface reset and delay quirk for AB13X USB Audio 2026-03-04 07:20:09 -05:00
tools rtla: Fix NULL pointer dereference in actions_parse 2026-03-04 07:20:13 -05:00
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 6.18.15 2026-02-27 16:05:10 -05:00
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.