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Thomas Gleixner e529888b7e perf/core: Prevent VMA split of buffer mappings 
commit b024d7b56c upstream.

The perf mmap code is careful about mmap()'ing the user page with the
ringbuffer and additionally the auxiliary buffer, when the event supports
it. Once the first mapping is established, subsequent mapping have to use
the same offset and the same size in both cases. The reference counting for
the ringbuffer and the auxiliary buffer depends on this being correct.

Though perf does not prevent that a related mapping is split via mmap(2),
munmap(2) or mremap(2). A split of a VMA results in perf_mmap_open() calls,
which take reference counts, but then the subsequent perf_mmap_close()
calls are not longer fulfilling the offset and size checks. This leads to
reference count leaks.

As perf already has the requirement for subsequent mappings to match the
initial mapping, the obvious consequence is that VMA splits, caused by
resizing of a mapping or partial unmapping, have to be prevented.

Implement the vm_operations_struct::may_split() callback and return
unconditionally -EINVAL.

That ensures that the mapping offsets and sizes cannot be changed after the
fact. Remapping to a different fixed address with the same size is still
possible as it takes the references for the new mapping and drops those of
the old mapping.

Fixes: 45bfb2e504 ("perf/core: Add AUX area to ring buffer for raw data streams")
Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-27504
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-08-15 12:14:09 +02:00
arch s390/mm: Allocate page table with PAGE_SIZE granularity 2025-08-15 12:14:07 +02:00
block block: ensure discard_granularity is zero when discard is not supported 2025-08-15 12:14:05 +02:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: ecdsa - Harden against integer overflows in DIV_ROUND_UP() 2025-07-17 18:37:24 +02:00
Documentation netlink: specs: ethtool: fix module EEPROM input/output arguments 2025-08-15 12:14:05 +02:00
drivers pptp: fix pptp_xmit() error path 2025-08-15 12:14:08 +02:00
fs smb: client: return an error if rdma_connect does not return within 5 seconds 2025-08-15 12:14:09 +02:00
include net: drop UFO packets in udp_rcv_segment() 2025-08-15 12:14:06 +02:00
init io_uring: fix breakage in EXPERT menu 2025-08-15 12:13:32 +02:00
io_uring io_uring/poll: fix POLLERR handling 2025-07-24 08:56:23 +02:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:11:22 +01:00
kernel perf/core: Prevent VMA split of buffer mappings 2025-08-15 12:14:09 +02:00
lib lib/alloc_tag: do not acquire non-existent lock in alloc_tag_top_users() 2025-07-17 18:37:14 +02:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm: khugepaged: fix call hpage_collapse_scan_file() for anonymous vma 2025-08-01 09:48:47 +01:00
net sunrpc: fix handling of server side tls alerts 2025-08-15 12:14:09 +02:00
rust rust: use #[used(compiler)] to fix build and modpost with Rust >= 1.89.0 2025-07-24 08:56:37 +02:00
samples samples: mei: Fix building on musl libc 2025-08-15 12:13:38 +02:00
scripts kconfig: qconf: fix ConfigList::updateListAllforAll() 2025-08-15 12:14:03 +02:00
security apparmor: Fix unaligned memory accesses in KUnit test 2025-08-15 12:13:59 +02:00
sound ALSA: hda/ca0132: Fix missing error handling in ca0132_alt_select_out() 2025-08-15 12:14:07 +02:00
tools perf record: Cache build-ID of hit DSOs only 2025-08-15 12:13:58 +02:00
usr kbuild: hdrcheck: fix cross build with clang 2025-03-13 13:02:18 +01:00
virt KVM: Allow CPU to reschedule while setting per-page memory attributes 2025-07-17 18:37:08 +02:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: give Clippy the minimum supported Rust version 2025-08-01 09:48:44 +01:00
.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 Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: introduce .clippy.toml 2025-03-13 13:01:42 +01:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -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 self from DSA entry 2024-11-03 12:52:38 -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 MAINTAINERS: Update Alexey Makhalov's email address 2025-05-22 14:29:46 +02:00
Makefile Linux 6.12.41 2025-08-01 09:48:47 +01:00
README README: Fix spelling 2024-03-18 03:36:32 -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 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.