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commit04ea3086c4upstream. Only the very first page of BPF ringbuf that contains consumer position counter is supposed to be mapped as writeable by user-space. Producer position is read-only and can be modified only by the kernel code. BPF ringbuf data pages are read-only as well and are not meant to be modified by user-code to maintain integrity of per-record headers. This patch allows to map only consumer position page as writeable and everything else is restricted to be read-only. remap_vmalloc_range() internally adds VM_DONTEXPAND, so all the established memory mappings can't be extended, which prevents any future violations through mremap()'ing. Fixes:457f44363a("bpf: Implement BPF ring buffer and verifier support for it") Reported-by: Ryota Shiga (Flatt Security) Reported-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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.