[PATCH] riscv: Randomize lower bits of stack address

[yunhui cui]

A gentle ping, Any more comments on this patch?

On Thu, Jul 11, 2024 at 2:09 PM yunhui cui <cuiyunhui at bytedance.com> wrote:
>
> Add punit in the loop.
>
>
> On Tue, Jun 25, 2024 at 11:05 AM Yunhui Cui <cuiyunhui at bytedance.com> wrote:
> >
> > Implement arch_align_stack() to randomize the lower bits
> > of the stack address.
> >
> > Signed-off-by: Yunhui Cui <cuiyunhui at bytedance.com>
> > ---
> >  arch/riscv/include/asm/exec.h | 8 ++++++++
> >  arch/riscv/kernel/process.c   | 9 +++++++++
> >  2 files changed, 17 insertions(+)
> >  create mode 100644 arch/riscv/include/asm/exec.h
> >
> > diff --git a/arch/riscv/include/asm/exec.h b/arch/riscv/include/asm/exec.h
> > new file mode 100644
> > index 000000000000..07d9942682e0
> > --- /dev/null
> > +++ b/arch/riscv/include/asm/exec.h
> > @@ -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 */
> > diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
> > index e4bc61c4e58a..e3142d8a6e28 100644
> > --- a/arch/riscv/kernel/process.c
> > +++ b/arch/riscv/kernel/process.c
> > @@ -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;
> >
> > --
> > 2.20.1
> >
>
> Thanks,
> Yunhui

Thanks,
Yunhui