kernel/linux
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2026-10-14 05:55:17 +00:00
Code Issues Releases Packages Activity
No description
1,236,056 commits 116 branches 5,791 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
Andrea Righi 22269c75ab kernfs: convert kernfs_idr_lock to an irq safe raw spinlock 
commit c312828c37 upstream.

bpf_cgroup_from_id() is basically a wrapper to cgroup_get_from_id(),
that is relying on kernfs to determine the right cgroup associated to
the target id.

As a kfunc, it has the potential to be attached to any function through
BPF, particularly in contexts where certain locks are held.

However, kernfs is not using an irq safe spinlock for kernfs_idr_lock,
that means any kernfs function that is acquiring this lock can be
interrupted and potentially hit bpf_cgroup_from_id() in the process,
triggering a deadlock.

For example, it is really easy to trigger a lockdep splat between
kernfs_idr_lock and rq->_lock, attaching a small BPF program to
__set_cpus_allowed_ptr_locked() that just calls bpf_cgroup_from_id():

 =====================================================
 WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected
 6.7.0-rc7-virtme #5 Not tainted
 -----------------------------------------------------
 repro/131 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
 ffffffffb2dc4578 (kernfs_idr_lock){+.+.}-{2:2}, at: kernfs_find_and_get_node_by_id+0x1d/0x80

 and this task is already holding:
 ffff911cbecaf218 (&rq->__lock){-.-.}-{2:2}, at: task_rq_lock+0x50/0xc0
 which would create a new lock dependency:
  (&rq->__lock){-.-.}-{2:2} -> (kernfs_idr_lock){+.+.}-{2:2}

 but this new dependency connects a HARDIRQ-irq-safe lock:
  (&rq->__lock){-.-.}-{2:2}

 ... which became HARDIRQ-irq-safe at:
   lock_acquire+0xbf/0x2b0
   _raw_spin_lock_nested+0x2e/0x40
   scheduler_tick+0x5d/0x170
   update_process_times+0x9c/0xb0
   tick_periodic+0x27/0xe0
   tick_handle_periodic+0x24/0x70
   __sysvec_apic_timer_interrupt+0x64/0x1a0
   sysvec_apic_timer_interrupt+0x6f/0x80
   asm_sysvec_apic_timer_interrupt+0x1a/0x20
   memcpy+0xc/0x20
   arch_dup_task_struct+0x15/0x30
   copy_process+0x1ce/0x1eb0
   kernel_clone+0xac/0x390
   kernel_thread+0x6f/0xa0
   kthreadd+0x199/0x230
   ret_from_fork+0x31/0x50
   ret_from_fork_asm+0x1b/0x30

 to a HARDIRQ-irq-unsafe lock:
  (kernfs_idr_lock){+.+.}-{2:2}

 ... which became HARDIRQ-irq-unsafe at:
 ...
   lock_acquire+0xbf/0x2b0
   _raw_spin_lock+0x30/0x40
   __kernfs_new_node.isra.0+0x83/0x280
   kernfs_create_root+0xf6/0x1d0
   sysfs_init+0x1b/0x70
   mnt_init+0xd9/0x2a0
   vfs_caches_init+0xcf/0xe0
   start_kernel+0x58a/0x6a0
   x86_64_start_reservations+0x18/0x30
   x86_64_start_kernel+0xc5/0xe0
   secondary_startup_64_no_verify+0x178/0x17b

 other info that might help us debug this:

  Possible interrupt unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(kernfs_idr_lock);
                                local_irq_disable();
                                lock(&rq->__lock);
                                lock(kernfs_idr_lock);
   <Interrupt>
     lock(&rq->__lock);

  *** DEADLOCK ***

Prevent this deadlock condition converting kernfs_idr_lock to a raw irq
safe spinlock.

The performance impact of this change should be negligible and it also
helps to prevent similar deadlock conditions with any other subsystems
that may depend on kernfs.

Fixes: 332ea1f697 ("bpf: Add bpf_cgroup_from_id() kfunc")
Cc: stable <stable@kernel.org>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20231229074916.53547-1-andrea.righi@canonical.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2024-01-25 15:45:09 -08:00
arch ARM: davinci: always select CONFIG_CPU_ARM926T 2024-01-25 15:44:57 -08:00
block blk-cgroup: fix rcu lockdep warning in blkg_lookup() 2024-01-25 15:44:57 -08:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto crypto: scomp - fix req->dst buffer overflow 2024-01-25 15:44:43 -08:00
Documentation media: dt-bindings: media: rkisp1: Fix the port description for the parallel interface 2024-01-25 15:45:03 -08:00
drivers class: fix use-after-free in class_register() 2024-01-25 15:45:09 -08:00
fs kernfs: convert kernfs_idr_lock to an irq safe raw spinlock 2024-01-25 15:45:09 -08:00
include clk: fixed-rate: fix clk_hw_register_fixed_rate_with_accuracy_parent_hw 2024-01-25 15:45:07 -08:00
init As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
io_uring io_uring/cmd: fix breakage in SOCKET_URING_OP_SIOC* implementation 2023-12-14 16:52:13 -07:00
ipc Many singleton patches against the MM code. The patch series which are 2023-11-02 19:38:47 -10:00
kernel bpf: Use c->unit_size to select target cache during free 2024-01-25 15:44:54 -08:00
lib test_bpf: Rename second ALU64_SMOD_X to ALU64_SMOD_K 2024-01-25 15:44:50 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/memory_hotplug: fix memmap_on_memory sysfs value retrieval 2024-01-20 11:53:02 +01:00
net ip6_tunnel: fix NEXTHDR_FRAGMENT handling in ip6_tnl_parse_tlv_enc_lim() 2024-01-25 15:44:57 -08:00
rust Kbuild updates for v6.7 2023-11-04 08:07:19 -10:00
samples Landlock updates for v6.7-rc1 2023-11-03 09:28:53 -10:00
scripts scripts/decode_stacktrace.sh: optionally use LLVM utilities 2024-01-20 11:53:02 +01:00
security selinux: Fix error priority for bind with AF_UNSPEC on PF_INET6 socket 2024-01-25 15:44:40 -08:00
sound ALSA: scarlett2: Add missing mutex lock around get meter levels 2024-01-25 15:45:07 -08:00
tools kselftest/alsa - conf: Stringify the printed errno in sysfs_get() 2024-01-25 15:45:08 -08:00
usr arch: Remove Itanium (IA-64) architecture 2023-09-11 08:13:17 +00:00
virt KVM/arm64 fixes for 6.7, part #2 2023-12-22 18:03:54 -05:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.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: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: generate kernel.spec in rpmbuild/SPECS/ 2023-10-03 20:49:09 +09:00
.mailmap 12 hotfixes. 2 are cc:stable and the remainder either address post-6.7 2024-01-05 13:46:18 -08:00
.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 12 hotfixes. 2 are cc:stable and the remainder either address post-6.7 2024-01-05 13:46:18 -08:00
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 12 hotfixes. 2 are cc:stable and the remainder either address post-6.7 2024-01-05 13:46:18 -08:00
Makefile Linux 6.7.1 2024-01-20 11:53:02 +01:00
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.