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Filename Latest commit message Latest commit date
Thomas Gleixner e4346ffec2 perf/core: Prevent VMA split of buffer mappings
commit b024d7b56c77191cde544f838debb7f8451cd0d6 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>
2025-08-28 16:21:23 +02:00
arch arch: powerpc: defconfig: Drop obsolete CONFIG_NET_CLS_TCINDEX 2025-08-28 16:21:19 +02:00
block
certs
crypto
Documentation scsi: ufs: core: Fix spelling of a sysfs attribute name 2025-07-17 18:24:58 +02:00
drivers pptp: fix pptp_xmit() error path 2025-08-28 16:21:22 +02:00
fs smb: client: let recv_done() cleanup before notifying the callers. 2025-08-28 16:21:22 +02:00
include net: drop UFO packets in udp_rcv_segment() 2025-08-28 16:21:22 +02:00
init bpfilter: match bit size of bpfilter_umh to that of the kernel 2025-07-17 18:24:51 +02:00
ipc
kernel perf/core: Prevent VMA split of buffer mappings 2025-08-28 16:21:23 +02:00
lib lib: test_objagg: Set error message in check_expect_hints_stats() 2025-07-17 18:24:56 +02:00
LICENSES
mm
net ipv6: reject malicious packets in ipv6_gso_segment() 2025-08-28 16:21:22 +02:00
samples samples: mei: Fix building on musl libc 2025-08-28 16:21:19 +02:00
scripts kbuild: use -MMD instead of -MD to exclude system headers from dependency 2025-07-17 18:24:51 +02:00
security
sound ASoC: ops: dynamically allocate struct snd_ctl_elem_value 2025-08-28 16:21:18 +02:00
tools perf tests bp_account: Fix leaked file descriptor 2025-08-28 16:21:20 +02:00
usr kbuild: hdrcheck: fix cross build with clang 2025-07-17 18:24:51 +02:00
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
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COPYING
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MAINTAINERS
Makefile Linux 5.4.296 2025-07-17 18:25:06 +02:00
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.