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When the kernel is compiled with -asan-stack=true, the address sanitizer will emit inline accesses to the shadow map. In other words, some shadow map accesses are not intercepted by the KASAN runtime, so they cannot be disabled even if the runtime is not yet initialized by kasan_init() at the end of hammer_time(). This went unnoticed because the loader will initialize all PML4 entries of the bootstrap page table to point to the same PDP page, so early shadow map accesses do not raise a page fault, though they are silently corrupting memory. In fact, when the loader does not copy the staging area, we do get a page fault since in that case only the first and last PML4Es are populated by the loader. But due to another bug, the loader always treated KASAN kernels as non-relocatable and thus always copied the staging area. It is not really practical to annotate hammer_time() and all callees with __nosanitizeaddress, so instead add some early initialization which creates a shadow for the boot stack used by hammer_time(). This is only needed by KASAN, not by KMSAN, but the shared pmap code handles both. Reported by: mhorne Reviewed by: kib MFC after: 1 month Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D35449
77 lines
2.5 KiB
C
77 lines
2.5 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2020 The FreeBSD Foundation
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*
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* This software was developed by Mark Johnston under sponsorship from the
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* FreeBSD Foundation.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef _MACHINE_ASAN_H_
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#define _MACHINE_ASAN_H_
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#ifdef KASAN
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#include <vm/vm.h>
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#include <vm/pmap.h>
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#include <vm/vm_page.h>
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#include <machine/vmparam.h>
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static inline vm_offset_t
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kasan_md_addr_to_shad(vm_offset_t addr)
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{
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return (((addr - VM_MIN_KERNEL_ADDRESS) >> KASAN_SHADOW_SCALE_SHIFT) +
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KASAN_MIN_ADDRESS);
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}
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static inline bool
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kasan_md_unsupported(vm_offset_t addr)
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{
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vm_offset_t kernmin;
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/*
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* The vm_page array is mapped at the beginning of the kernel map, but
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* accesses to the array are not validated for now. Handle the fact
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* that KASAN must validate accesses before the vm_page array is
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* initialized.
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*/
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kernmin = vm_page_array == NULL ? VM_MIN_KERNEL_ADDRESS :
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(vm_offset_t)(vm_page_array + vm_page_array_size);
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return (addr < kernmin || addr >= VM_MAX_KERNEL_ADDRESS);
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}
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static inline void
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kasan_md_init(void)
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{
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}
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static inline void
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kasan_md_init_early(vm_offset_t bootstack, size_t size)
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{
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kasan_shadow_map(bootstack, size);
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}
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#endif /* KASAN */
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#endif /* !_MACHINE_ASAN_H_ */
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