linux/arch/arm64/include/asm/vmap_stack.h
Andrey Konovalov 51fb34de2a kasan, arm64: reset pointer tags of vmapped stacks
Once tag-based KASAN modes start tagging vmalloc() allocations, kernel
stacks start getting tagged if CONFIG_VMAP_STACK is enabled.

Reset the tag of kernel stack pointers after allocation in
arch_alloc_vmap_stack().

For SW_TAGS KASAN, when CONFIG_KASAN_STACK is enabled, the instrumentation
can't handle the SP register being tagged.

For HW_TAGS KASAN, there's no instrumentation-related issues.  However,
the impact of having a tagged SP register needs to be properly evaluated,
so keep it non-tagged for now.

Note, that the memory for the stack allocation still gets tagged to catch
vmalloc-into-stack out-of-bounds accesses.

[andreyknvl@google.com: fix case when a stack is retrieved from cached_stacks]
  Link: https://lkml.kernel.org/r/f50c5f96ef896d7936192c888b0c0a7674e33184.1644943792.git.andreyknvl@google.com
[dan.carpenter@oracle.com: remove unnecessary check in alloc_thread_stack_node()]
  Link: https://lkml.kernel.org/r/20220301080706.GB17208@kili

Link: https://lkml.kernel.org/r/698c5ab21743c796d46c15d075b9481825973e34.1643047180.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marco Elver <elver@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-03-24 19:06:47 -07:00

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C

/* SPDX-License-Identifier: GPL-2.0 */
// Copyright (C) 2017 Arm Ltd.
#ifndef __ASM_VMAP_STACK_H
#define __ASM_VMAP_STACK_H
#include <linux/bug.h>
#include <linux/gfp.h>
#include <linux/kconfig.h>
#include <linux/vmalloc.h>
#include <linux/pgtable.h>
#include <asm/memory.h>
#include <asm/thread_info.h>
/*
* To ensure that VMAP'd stack overflow detection works correctly, all VMAP'd
* stacks need to have the same alignment.
*/
static inline unsigned long *arch_alloc_vmap_stack(size_t stack_size, int node)
{
void *p;
BUILD_BUG_ON(!IS_ENABLED(CONFIG_VMAP_STACK));
p = __vmalloc_node(stack_size, THREAD_ALIGN, THREADINFO_GFP, node,
__builtin_return_address(0));
return kasan_reset_tag(p);
}
#endif /* __ASM_VMAP_STACK_H */