kernel/linux
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2026-10-18 19:12:56 +00:00
Code Issues Releases Packages Activity
No description
1,074,825 commits 116 branches 5,798 tags 5.6 GiB
  • C 96.9%
  • Assembly 0.9%
  • Rust 0.6%
  • Shell 0.6%
  • Python 0.5%
  • Other 0.3%
Find a file
Jeongjun Park 240325993e ptp: prevent possible ABBA deadlock in ptp_clock_freerun() 
[ Upstream commit 2efe41234d ]

syzbot reported the following ABBA deadlock:

       CPU0                           CPU1
       ----                           ----
  n_vclocks_store()
    lock(&ptp->n_vclocks_mux) [1]
        (physical clock)
                                     pc_clock_adjtime()
                                       lock(&clk->rwsem) [2]
                                        (physical clock)
                                       ...
                                       ptp_clock_freerun()
                                         ptp_vclock_in_use()
                                           lock(&ptp->n_vclocks_mux) [3]
                                              (physical clock)
    ptp_clock_unregister()
      posix_clock_unregister()
        lock(&clk->rwsem) [4]
          (virtual clock)

Since ptp virtual clock is registered only under ptp physical clock, both
ptp_clock and posix_clock must be physical clocks for ptp_vclock_in_use()
to lock &ptp->n_vclocks_mux and check ptp->n_vclocks.

However, when unregistering vclocks in n_vclocks_store(), the locking
ptp->n_vclocks_mux is a physical clock lock, but clk->rwsem of
ptp_clock_unregister() called through device_for_each_child_reverse()
is a virtual clock lock.

Therefore, clk->rwsem used in CPU0 and clk->rwsem used in CPU1 are
different locks, but in lockdep, a false positive occurs because the
possibility of deadlock is determined through lock-class.

To solve this, lock subclass annotation must be added to the posix_clock
rwsem of the vclock.

Reported-by: syzbot+7cfb66a237c4a5fb22ad@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=7cfb66a237c4a5fb22ad
Fixes: 73f37068d5 ("ptp: support ptp physical/virtual clocks conversion")
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20250728062649.469882-1-aha310510@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-08-28 16:24:16 +02:00
arch MIPS: mm: tlb-r4k: Uniquify TLB entries on init 2025-08-28 16:24:14 +02:00
block block: default BLOCK_LEGACY_AUTOLOAD to y 2025-06-27 11:05:34 +01:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto crypto: xts - Only add ecb if it is not already there 2025-06-27 11:05:10 +01:00
Documentation Documentation: ACPI: Fix parent device references 2025-08-28 16:24:15 +02:00
drivers
fs eventpoll: Fix semi-unbounded recursion 2025-08-28 16:24:15 +02:00
include io_uring: don't use int for ABI 2025-08-28 16:24:15 +02:00
init sched/isolation: Make CONFIG_CPU_ISOLATION depend on CONFIG_SMP 2025-05-02 07:44:36 +02:00
io_uring io_uring: fix possible deadlock in io_register_iowq_max_workers() 2024-11-17 15:06:25 +01:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:05:26 +01:00
kernel perf/core: Prevent VMA split of buffer mappings 2025-08-28 16:24:14 +02:00
lib lib: bitmap: Introduce node-aware alloc API 2025-08-28 16:24:02 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm/hmm: move pmd_to_hmm_pfn_flags() to the respective #ifdeffery 2025-08-28 16:24:14 +02:00
net sctp: linearize cloned gso packets in sctp_rcv 2025-08-28 16:24:16 +02:00
samples samples: mei: Fix building on musl libc 2025-08-28 16:24:07 +02:00
scripts kconfig: qconf: fix ConfigList::updateListAllforAll() 2025-08-28 16:24:12 +02:00
security apparmor: ensure WB_HISTORY_SIZE value is a power of 2 2025-08-28 16:24:11 +02:00
sound ALSA: usb-audio: Validate UAC3 cluster segment descriptors 2025-08-28 16:24:15 +02:00
tools selftests/perf_events: Add a mmap() correctness test 2025-08-28 16:24:14 +02:00
usr kbuild: hdrcheck: fix cross build with clang 2025-06-27 11:05:22 +01:00
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-10-22 15:40:41 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-17 15:11:10 +02:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS trace: Relocate event helper files 2024-04-10 16:19:24 +02:00
Makefile Linux 5.15.189 2025-07-17 18:30:55 +02:00
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.