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Jiri Olsa d0d2df38f5 bpf: Synchronize dispatcher update with bpf_dispatcher_xdp_func 
commit 4121d4481b upstream.

Hao Sun reported crash in dispatcher image [1].

Currently we don't have any sync between bpf_dispatcher_update and
bpf_dispatcher_xdp_func, so following race is possible:

 cpu 0:                               cpu 1:

 bpf_prog_run_xdp
   ...
   bpf_dispatcher_xdp_func
     in image at offset 0x0

                                      bpf_dispatcher_update
                                        update image at offset 0x800
                                      bpf_dispatcher_update
                                        update image at offset 0x0

     in image at offset 0x0 -> crash

Fixing this by synchronizing dispatcher image update (which is done
in bpf_dispatcher_update function) with bpf_dispatcher_xdp_func that
reads and execute the dispatcher image.

Calling synchronize_rcu after updating and installing new image ensures
that readers leave old image before it's changed in the next dispatcher
update. The update itself is locked with dispatcher's mutex.

The bpf_prog_run_xdp is called under local_bh_disable and synchronize_rcu
will wait for it to leave [2].

[1] https://lore.kernel.org/bpf/Y5SFho7ZYXr9ifRn@krava/T/#m00c29ece654bc9f332a17df493bbca33e702896c
[2] https://lore.kernel.org/bpf/0B62D35A-E695-4B7A-A0D4-774767544C1A@gmail.com/T/#mff43e2c003ae99f4a38f353c7969be4c7162e877

Reported-by: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20221214123542.1389719-1-jolsa@kernel.org
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reported-by: syzbot+08ba1e474d350b613604@syzkaller.appspotmail.com
Signed-off-by: Sergio González Collado <sergio.collado@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2024-08-03 08:49:45 +02:00
arch MIPS: Loongson64: Test register availability before use 2024-08-03 08:49:45 +02:00
block block: initialize integrity buffer to zero before writing it to media 2024-08-03 08:48:53 +02:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: aead,cipher - zeroize key buffer after use 2024-07-11 12:47:05 +02:00
Documentation dt-bindings: thermal: correct thermal zone node name limit 2024-08-03 08:49:30 +02:00
drivers rbd: don't assume RBD_LOCK_STATE_LOCKED for exclusive mappings 2024-08-03 08:49:45 +02:00
fs f2fs: fix return value of f2fs_convert_inline_inode() 2024-08-03 08:49:38 +02:00
include perf: Fix event leak upon exec and file release 2024-08-03 08:49:41 +02:00
init smp: Provide 'setup_max_cpus' definition on UP too 2024-06-16 13:41:42 +02:00
io_uring io_uring: tighten task exit cancellations 2024-08-03 08:49:34 +02:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel bpf: Synchronize dispatcher update with bpf_dispatcher_xdp_func 2024-08-03 08:49:45 +02:00
lib kobject_uevent: Fix OOB access within zap_modalias_env() 2024-08-03 08:49:39 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm/numa_balancing: teach mpol_to_str about the balancing mode 2024-08-03 08:49:40 +02:00
net ipv6: take care of scope when choosing the src addr 2024-08-03 08:49:31 +02:00
rust rust: macros: fix soundness issue in module! macro 2024-05-17 11:56:17 +02:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-23 09:12:28 +01:00
scripts kbuild: Fix '-S -c' in x86 stack protector scripts 2024-08-03 08:49:39 +02:00
security task_work: s/task_work_cancel()/task_work_cancel_func()/ 2024-08-03 08:49:33 +02:00
sound ASoC: amd: yc: Support mic on Lenovo Thinkpad E16 Gen 2 2024-08-03 08:49:39 +02:00
tools selftests/sigaltstack: Fix ppc64 GCC build 2024-08-03 08:49:43 +02:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-06-27 13:46:21 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.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 dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -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 MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
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 MAINTAINERS: add leah to 6.1 MAINTAINERS file 2024-05-17 11:56:16 +02:00
Makefile Linux 6.1.102 2024-07-27 11:32:20 +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.