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From:   David Abdurachmanov <david.abdurachmanov@gmail.com>
Date:   Fri, 29 Mar 2019 18:52:18 +0100
Message-ID: <CAEn-LTpY6Tto1N9irXJeOb4iB=qSYhb=jM0E=Z9ppumbPX6GSw@mail.gmail.com>
Subject: Re: [PATCH] riscv: fix syscall_get_arguments() and syscall_set_arguments()
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     "Dmitry V. Levin" <ldv@altlinux.org>,
        Will Drewry <wad@chromium.org>,
        Kees Cook <keescook@chromium.org>,
        Palmer Dabbelt <palmer@sifive.com>,
        linux-kernel@vger.kernel.org,
        Andy Lutomirski <luto@amacapital.net>,
        Ingo Molnar <mingo@redhat.com>, linux-riscv@lists.infradead.org
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On Fri, Mar 29, 2019 at 6:15 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Fri, 29 Mar 2019 20:12:21 +0300
> "Dmitry V. Levin" <ldv@altlinux.org> wrote:
>
> > RISC-V syscall arguments are located in orig_a0,a1..a5 fields
> > of struct pt_regs.
> >
> > Due to an off-by-one bug and a bug in pointer arithmetic
> > syscall_get_arguments() was reading s3..s7 fields instead of a1..a5.
> > Likewise, syscall_set_arguments() was writing s3..s7 fields
> > instead of a1..a5.
>
> Should I add this to my series? And then rebase on top of it?

I have alternative version posted in December part of SECCOMP
patchset which is based on arm64 implementation.

http://lists.infradead.org/pipermail/linux-riscv/2018-December/002450.html

I noticed that SECCOMP wasn't working properly if filters were
checking syscall arguments, because populated arguments were wrong.

Btw, I plan to send v2 of SECCOMP patchset soonish.

david

>
> -- Steve
>
> >
> > Fixes: e2c0cdfba7f69 ("RISC-V: User-facing API")
> > Cc: Steven Rostedt <rostedt@goodmis.org>
> > Cc: Ingo Molnar <mingo@redhat.com>
> > Cc: Kees Cook <keescook@chromium.org>
> > Cc: Andy Lutomirski <luto@amacapital.net>
> > Cc: Will Drewry <wad@chromium.org>
> > Cc: linux-riscv@lists.infradead.org
> > Cc: stable@vger.kernel.org # v4.15+
> > Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
> > ---
> >  arch/riscv/include/asm/syscall.h | 12 +++++++-----
> >  1 file changed, 7 insertions(+), 5 deletions(-)
> >
> > diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h
> > index bba3da6ef157..6ea9e1804233 100644
> > --- a/arch/riscv/include/asm/syscall.h
> > +++ b/arch/riscv/include/asm/syscall.h
> > @@ -79,10 +79,11 @@ static inline void syscall_get_arguments(struct task_struct *task,
> >       if (i == 0) {
> >               args[0] = regs->orig_a0;
> >               args++;
> > -             i++;
> >               n--;
> > +     } else {
> > +             i--;
> >       }
> > -     memcpy(args, &regs->a1 + i * sizeof(regs->a1), n * sizeof(args[0]));
> > +     memcpy(args, &regs->a1 + i, n * sizeof(args[0]));
> >  }
> >
> >  static inline void syscall_set_arguments(struct task_struct *task,
> > @@ -94,10 +95,11 @@ static inline void syscall_set_arguments(struct task_struct *task,
> >          if (i == 0) {
> >                  regs->orig_a0 = args[0];
> >                  args++;
> > -                i++;
> >                  n--;
> > -        }
> > -     memcpy(&regs->a1 + i * sizeof(regs->a1), args, n * sizeof(regs->a0));
> > +     } else {
> > +             i--;
> > +     }
> > +     memcpy(&regs->a1 + i, args, n * sizeof(regs->a1));
> >  }
> >
> >  static inline int syscall_get_arch(void)
>
>
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