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![Alexander Potapenko](/assets/img/avatar_default.png)
For each memory location KernelMemorySanitizer maintains two types of metadata: 1. The so-called shadow of that location - а byte:byte mapping describing whether or not individual bits of memory are initialized (shadow is 0) or not (shadow is 1). 2. The origins of that location - а 4-byte:4-byte mapping containing 4-byte IDs of the stack traces where uninitialized values were created. Each struct page now contains pointers to two struct pages holding KMSAN metadata (shadow and origins) for the original struct page. Utility routines in mm/kmsan/core.c and mm/kmsan/shadow.c handle the metadata creation, addressing, copying and checking. mm/kmsan/report.c performs error reporting in the cases an uninitialized value is used in a way that leads to undefined behavior. KMSAN compiler instrumentation is responsible for tracking the metadata along with the kernel memory. mm/kmsan/instrumentation.c provides the implementation for instrumentation hooks that are called from files compiled with -fsanitize=kernel-memory. To aid parameter passing (also done at instrumentation level), each task_struct now contains a struct kmsan_task_state used to track the metadata of function parameters and return values for that task. Finally, this patch provides CONFIG_KMSAN that enables KMSAN, and declares CFLAGS_KMSAN, which are applied to files compiled with KMSAN. The KMSAN_SANITIZE:=n Makefile directive can be used to completely disable KMSAN instrumentation for certain files. Similarly, KMSAN_ENABLE_CHECKS:=n disables KMSAN checks and makes newly created stack memory initialized. Users can also use functions from include/linux/kmsan-checks.h to mark certain memory regions as uninitialized or initialized (this is called "poisoning" and "unpoisoning") or check that a particular region is initialized. Link: https://lkml.kernel.org/r/20220915150417.722975-12-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Acked-by: Marco Elver <elver@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Eric Biggers <ebiggers@google.com> Cc: Eric Biggers <ebiggers@kernel.org> Cc: Eric Dumazet <edumazet@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Ilya Leoshkevich <iii@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kees Cook <keescook@chromium.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
35 lines
882 B
C
35 lines
882 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* A minimal header declaring types added by KMSAN to existing kernel structs.
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*
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* Copyright (C) 2017-2022 Google LLC
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* Author: Alexander Potapenko <glider@google.com>
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*
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*/
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#ifndef _LINUX_KMSAN_TYPES_H
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#define _LINUX_KMSAN_TYPES_H
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/* These constants are defined in the MSan LLVM instrumentation pass. */
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#define KMSAN_RETVAL_SIZE 800
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#define KMSAN_PARAM_SIZE 800
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struct kmsan_context_state {
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char param_tls[KMSAN_PARAM_SIZE];
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char retval_tls[KMSAN_RETVAL_SIZE];
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char va_arg_tls[KMSAN_PARAM_SIZE];
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char va_arg_origin_tls[KMSAN_PARAM_SIZE];
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u64 va_arg_overflow_size_tls;
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char param_origin_tls[KMSAN_PARAM_SIZE];
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u32 retval_origin_tls;
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};
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#undef KMSAN_PARAM_SIZE
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#undef KMSAN_RETVAL_SIZE
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struct kmsan_ctx {
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struct kmsan_context_state cstate;
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int kmsan_in_runtime;
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bool allow_reporting;
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};
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#endif /* _LINUX_KMSAN_TYPES_H */
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