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linux-next/arch/um/kernel/maccess.c
Christoph Hellwig 98a23609b1 maccess: always use strict semantics for probe_kernel_read
Except for historical confusion in the kprobes/uprobes and bpf tracers,
which has been fixed now, there is no good reason to ever allow user
memory accesses from probe_kernel_read.  Switch probe_kernel_read to only
read from kernel memory.

[akpm@linux-foundation.org: update it for "mm, dump_page(): do not crash with invalid mapping pointer"]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200521152301.2587579-17-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-09 09:39:15 -07:00

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C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2013 Richard Weinberger <richrd@nod.at>
*/
#include <linux/uaccess.h>
#include <linux/kernel.h>
#include <os.h>
bool probe_kernel_read_allowed(const void *src, size_t size)
{
void *psrc = (void *)rounddown((unsigned long)src, PAGE_SIZE);
if ((unsigned long)src < PAGE_SIZE || size <= 0)
return false;
if (os_mincore(psrc, size + src - psrc) <= 0)
return false;
return true;
}