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622754e84b
The RNG always mixes in the Linux version extremely early in boot. It also always includes a cycle counter, not only during early boot, but each and every time it is invoked prior to being fully initialized. Together, this means that the use of additional xors inside of the various stackprotector.h files is superfluous and over-complicated. Instead, we can get exactly the same thing, but better, by just calling `get_random_canary()`. Acked-by: Guo Ren <guoren@kernel.org> # for csky Acked-by: Catalin Marinas <catalin.marinas@arm.com> # for arm64 Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
38 lines
1.1 KiB
C
38 lines
1.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* GCC stack protector support.
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*
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* Stack protector works by putting predefined pattern at the start of
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* the stack frame and verifying that it hasn't been overwritten when
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* returning from the function. The pattern is called stack canary
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* and gcc expects it to be defined by a global variable called
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* "__stack_chk_guard" on ARM. This prevents SMP systems from using a
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* different value for each task unless we enable a GCC plugin that
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* replaces these symbol references with references to each task's own
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* value.
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*/
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#ifndef _ASM_STACKPROTECTOR_H
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#define _ASM_STACKPROTECTOR_H 1
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#include <asm/thread_info.h>
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extern unsigned long __stack_chk_guard;
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/*
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* Initialize the stackprotector canary value.
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*
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* NOTE: this must only be called from functions that never return,
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* and it must always be inlined.
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*/
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static __always_inline void boot_init_stack_canary(void)
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{
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unsigned long canary = get_random_canary();
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current->stack_canary = canary;
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#ifndef CONFIG_STACKPROTECTOR_PER_TASK
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__stack_chk_guard = current->stack_canary;
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#endif
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}
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#endif /* _ASM_STACKPROTECTOR_H */
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