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riscv: Randomize lower bits of stack address

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Implement arch_align_stack() to randomize the lower bits
of the stack address.

Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
Link: https://lore.kernel.org/r/20240625030502.68988-1-cuiyunhui@bytedance.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Yunhui Cui 2024-06-25 11:05:02 +08:00 committed by Palmer Dabbelt
parent 11c2dbd7f2
commit 048e2906d4
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2 changed files with 17 additions and 0 deletions
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8
arch/riscv/include/asm/exec.h Normal file
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@ -0,0 +1,8 @@
/* SPDX-License-Identifier: GPL-2.0-only */
#ifndef __ASM_EXEC_H
#define __ASM_EXEC_H
extern unsigned long arch_align_stack(unsigned long sp);
#endif /* __ASM_EXEC_H */

9
arch/riscv/kernel/process.c
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@ -15,6 +15,7 @@
#include <linux/tick.h>
#include <linux/ptrace.h>
#include <linux/uaccess.h>
#include <linux/personality.h>
#include <asm/unistd.h>
#include <asm/processor.h>
@ -26,6 +27,7 @@
#include <asm/cpuidle.h>
#include <asm/vector.h>
#include <asm/cpufeature.h>
#include <asm/exec.h>
#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
#include <linux/stackprotector.h>
@ -99,6 +101,13 @@ void show_regs(struct pt_regs *regs)
dump_backtrace(regs, NULL, KERN_DEFAULT);
}
unsigned long arch_align_stack(unsigned long sp)
{
if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
sp -= get_random_u32_below(PAGE_SIZE);
return sp & ~0xf;
}
#ifdef CONFIG_COMPAT
static bool compat_mode_supported __read_mostly;