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Luis Gerhorst 3d71b8b9ab bpf: Fix state use-after-free on push_stack() err
Without this, `state->speculative` is used after the cleanup cycles in
push_stack() or push_async_cb() freed `env->cur_state` (i.e., `state`).
Avoid this by relying on the short-circuit logic to only access `state`
if the error is recoverable (and make sure it never is after push_*()
failed).

push_*() callers must always return an error for which
error_recoverable_with_nospec(err) is false if push_*() returns NULL,
otherwise we try to recover and access the stale `state`. This is only
violated by sanitize_ptr_alu(), thus also fix this case to return
-ENOMEM.

state->speculative does not make sense if the error path of push_*()
ran. In that case, `state->speculative &&
error_recoverable_with_nospec(err)` as a whole should already never
evaluate to true (because all cases where push_stack() fails must return
-ENOMEM/-EFAULT). As mentioned, this is only violated by the
push_stack() call in sanitize_speculative_path() which returns -EACCES
without [1] (through REASON_STACK in sanitize_err() after
sanitize_ptr_alu()). To fix this, return -ENOMEM for REASON_STACK (which
is also the behavior we will have after [1]).

Checked that it fixes the syzbot reproducer as expected.

[1] https://lore.kernel.org/all/20250603213232.339242-1-luis.gerhorst@fau.de/

Fixes: d6f1c85f22 ("bpf: Fall back to nospec for Spectre v1")
Reported-by: syzbot+b5eb72a560b8149a1885@syzkaller.appspotmail.com
Reported-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/all/38862a832b91382cddb083dddd92643bed0723b8.camel@gmail.com/
Signed-off-by: Luis Gerhorst <luis.gerhorst@fau.de>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250611210728.266563-1-luis.gerhorst@fau.de
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-06-12 16:52:43 -07:00
arch bpf, arm64, powerpc: Change nospec to include v1 barrier 2025-06-09 20:11:09 -07:00
block - dm: better error handling when reloading a table 2025-06-03 15:54:46 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto EFI updates for v6.16 2025-05-30 12:42:57 -07:00
Documentation bpf, doc: Improve wording of docs 2025-06-11 12:30:41 -07:00
drivers RTC for 6.16 2025-06-05 08:54:47 -07:00
fs four smb3 server fixes 2025-06-04 19:23:37 -07:00
include bpf: include backedges in peak_states stat 2025-06-12 16:52:43 -07:00
init Rust changes for v6.16 2025-06-04 21:18:37 -07:00
io_uring Networking changes for 6.16. 2025-05-28 15:24:36 -07:00
ipc - The 3 patch series "hung_task: extend blocking task stacktrace dump to 2025-05-31 19:12:53 -07:00
kernel bpf: Fix state use-after-free on push_stack() err 2025-06-12 16:52:43 -07:00
lib bitmap-for-6.16 2025-06-03 07:39:23 -07:00
LICENSES LICENSES: add CC0-1.0 license text 2025-05-21 14:54:17 +02:00
mm slab updates for 6.16 2025-06-04 08:59:59 -07:00
net NFS Clent Updates for Linux 6.16 2025-06-03 16:13:32 -07:00
rust Rust changes for v6.16 2025-06-04 21:18:37 -07:00
samples - The 3 patch series "hung_task: extend blocking task stacktrace dump to 2025-05-31 19:12:53 -07:00
scripts Rust changes for v6.16 2025-06-04 21:18:37 -07:00
security require gcc-8 and binutils-2.30 2025-05-31 08:16:52 -07:00
sound soundwire updates for 6.16 2025-06-05 08:07:24 -07:00
tools selftests/bpf: tests with a loop state missing read/precision mark 2025-06-12 16:52:43 -07:00
usr usr/include: openrisc: don't HDRTEST bpf_perf_event.h 2025-05-12 15:03:17 +09:00
virt Merge branch 'kvm-lockdep-common' into HEAD 2025-05-28 06:29:17 -04:00
.clang-format Linux 6.15-rc5 2025-05-06 16:39:25 +10:00
.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: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore .gitignore: ignore Python compiled bytecode 2025-04-24 10:12:46 -06:00
.mailmap Rust changes for v6.16 2025-06-04 21:18:37 -07:00
.pylintrc docs: add a .pylintrc file with sys path for docs scripts 2025-04-09 12:10:33 -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 Update Christoph's Email address and make it consistent 2025-05-12 23:50:31 -07:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS dmaengine updates for v6.16 2025-06-05 08:49:30 -07:00
Makefile A moderately busy cycle for documentation this time around: 2025-05-27 11:22:19 -07:00
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.