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Jesper Dangaard Brouer a14602fcae veth: reduce XDP no_direct return section to fix race
As explain in commit fa349e396e ("veth: Fix race with AF_XDP exposing
old or uninitialized descriptors") for veth there is a chance after
napi_complete_done() that another CPU can manage start another NAPI
instance running veth_pool(). For NAPI this is correctly handled as the
napi_schedule_prep() check will prevent multiple instances from getting
scheduled, but for the remaining code in veth_pool() this can run
concurrent with the newly started NAPI instance.

The problem/race is that xdp_clear_return_frame_no_direct() isn't
designed to be nested.

Prior to commit 401cb7dae8 ("net: Reference bpf_redirect_info via
task_struct on PREEMPT_RT.") the temporary BPF net context
bpf_redirect_info was stored per CPU, where this wasn't an issue. Since
this commit the BPF context is stored in 'current' task_struct. When
running veth in threaded-NAPI mode, then the kthread becomes the storage
area. Now a race exists between two concurrent veth_pool() function calls
one exiting NAPI and one running new NAPI, both using the same BPF net
context.

Race is when another CPU gets within the xdp_set_return_frame_no_direct()
section before exiting veth_pool() calls the clear-function
xdp_clear_return_frame_no_direct().

Fixes: 401cb7dae8 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.")
Signed-off-by: Jesper Dangaard Brouer <hawk@kernel.org>
Link: https://patch.msgid.link/176356963888.337072.4805242001928705046.stgit@firesoul
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-20 18:44:32 -08:00
arch soc: fixes for 6.18, part 3 2025-11-19 09:36:04 -08:00
block vfs-6.18-rc7.fixes 2025-11-17 09:11:27 -08:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push contains the following changes: 2025-10-10 08:56:16 -07:00
Documentation sound fixes for 6.18-rc6 2025-11-14 12:50:08 -08:00
drivers veth: reduce XDP no_direct return section to fix race 2025-11-20 18:44:32 -08:00
fs vfs-6.18-rc7.fixes 2025-11-17 09:11:27 -08:00
include Including fixes from IPsec and wireless. 2025-11-20 08:52:07 -08:00
init printk changes for 6.18 2025-10-04 11:13:11 -07:00
io_uring io_uring/rsrc: don't use blk_rq_nr_phys_segments() as number of bvecs 2025-11-12 08:25:33 -07:00
ipc namespace-6.18-rc1 2025-09-29 11:20:29 -07:00
kernel vfs-6.18-rc7.fixes 2025-11-17 09:11:27 -08:00
lib lib/test_kho: check if KHO is enabled 2025-11-15 10:52:01 -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 memblock: fix memblock_estimated_nr_free_pages() for soft-reserved memory 2025-11-19 08:27:05 -08:00
net net: atm: fix incorrect cleanup function call in error path 2025-11-20 18:09:49 -08:00
rust rust: Add -fno-isolate-erroneous-paths-dereference to bindgen_skip_c_flags 2025-11-10 08:37:06 +08:00
samples Char/Misc/IIO/Binder changes for 6.18-rc1 2025-10-04 16:26:32 -07:00
scripts Rust fixes for v6.18 (2nd) 2025-11-14 15:36:15 -08:00
security landlock: fix splats from iput() after it started calling might_sleep() 2025-11-12 10:47:42 +01:00
sound ALSA: usb-audio: Add native DSD quirks for PureAudio DAC series 2025-11-14 14:19:47 +01:00
tools Including fixes from IPsec and wireless. 2025-11-20 08:52:07 -08:00
usr gen_init_cpio: Ignore fsync() returning EINVAL on pipes 2025-10-07 09:53:05 -07:00
virt KVM: guest_memfd: Remove bindings on memslot deletion when gmem is dying 2025-11-04 09:16:53 -08:00
.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
.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 soc: fixes for 6.18, part 3 2025-11-19 09:36:04 -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 Including fixes from IPsec and wireless. 2025-11-20 08:52:07 -08:00
Makefile Linux 6.18-rc6 2025-11-16 14:25:38 -08:00
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.