From: David Abdurachmanov <david.abdurachmanov@gmail.com>
To: Andreas Schwab <schwab@suse.de>
Cc: Albert Ou <aou@eecs.berkeley.edu>,
Kees Cook <keescook@chromium.org>,
David Abdurachmanov <david.abdurachmanov@sifive.com>,
Anup Patel <Anup.Patel@wdc.com>,
"linux-kernel@vger.kernel.org List"
<linux-kernel@vger.kernel.org>,
linux-riscv <linux-riscv@lists.infradead.org>,
Vincent Chen <vincent.chen@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Thomas Gleixner <tglx@linutronix.de>,
Bin Meng <bmeng.cn@gmail.com>,
Valentin Schneider <valentin.schneider@arm.com>
Subject: Re: [PATCH] riscv: reject invalid syscalls below -1
Date: Wed, 18 Dec 2019 12:06:57 +0200 [thread overview]
Message-ID: <CAEn-LTojXuAbY31nReCsbE=7Q9PkuKexAttTc+35ZFn7SLG-_w@mail.gmail.com> (raw)
In-Reply-To: <mvmo8w63r1d.fsf@suse.de>
On Wed, Dec 18, 2019 at 11:46 AM Andreas Schwab <schwab@suse.de> wrote:
>
> On Dez 18 2019, David Abdurachmanov wrote:
>
> > diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
> > index a1349ca64669..e163b7b64c86 100644
> > --- a/arch/riscv/kernel/entry.S
> > +++ b/arch/riscv/kernel/entry.S
> > @@ -246,6 +246,7 @@ check_syscall_nr:
> > */
> > li t1, -1
> > beq a7, t1, ret_from_syscall_rejected
> > + blt a7, t1, 1f
>
> How about using bgeu instead in the preceding check?
The syscall number could be -1 if tracer rejected it.
We could do:
li t0, __NR_syscalls
[..]
// first check if syscall was rejected
li t1, -1
beq a7, t1, ret_from_syscall_rejected
// then check the bounds
bgeu a7, t0, 1f
>
> /*
> * Syscall number held in a7.
> * If syscall number is above allowed value, redirect to ni_syscall.
> */
> bge a7, t0, 1f
>
> Andreas.
>
> --
> Andreas Schwab, SUSE Labs, schwab@suse.de
> GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7
> "And now for something completely different."
next prev parent reply other threads:[~2019-12-18 10:07 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-18 8:47 [PATCH] riscv: reject invalid syscalls below -1 David Abdurachmanov
2019-12-18 9:46 ` Andreas Schwab
2019-12-18 10:06 ` David Abdurachmanov [this message]
2019-12-18 10:35 ` Andreas Schwab
2019-12-28 6:02 ` Paul Walmsley
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