From: Guo Ren <guoren@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: arnd@arndb.de, palmer@rivosinc.com, tglx@linutronix.de,
luto@kernel.org, conor.dooley@microchip.com, heiko@sntech.de,
jszhang@kernel.org, lazyparser@gmail.com, falcon@tinylab.org,
chenhuacai@kernel.org, apatel@ventanamicro.com,
atishp@atishpatra.org, palmer@dabbelt.com,
paul.walmsley@sifive.com, mark.rutland@arm.com,
zouyipeng@huawei.com, bigeasy@linutronix.de,
David.Laight@aculab.com, linux-arch@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org,
Guo Ren <guoren@linux.alibaba.com>,
keescook@chromium.org
Subject: Re: [PATCH V5 08/11] riscv: Support HAVE_IRQ_EXIT_ON_IRQ_STACK
Date: Wed, 21 Sep 2022 14:16:03 +0800 [thread overview]
Message-ID: <CAJF2gTTFLEV47OT6hM0DwaSbm+4-Q_s+x0Wc3MFjpv1Kr4rbKQ@mail.gmail.com> (raw)
In-Reply-To: <Yyls+xIUsLCIa7pj@hirez.programming.kicks-ass.net>
On Tue, Sep 20, 2022 at 3:34 PM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Tue, Sep 20, 2022 at 09:27:51AM +0200, Peter Zijlstra wrote:
> > On Tue, Sep 20, 2022 at 02:08:55PM +0800, Guo Ren wrote:
> > > On Mon, Sep 19, 2022 at 9:45 PM Peter Zijlstra <peterz@infradead.org> wrote:
> > > >
> > > > On Sun, Sep 18, 2022 at 11:52:43AM -0400, guoren@kernel.org wrote:
> > > >
> > > > > +ENTRY(call_on_stack)
> > > > > + /* Create a frame record to save our ra and fp */
> > > > > + addi sp, sp, -RISCV_SZPTR
> > > > > + REG_S ra, (sp)
> > > > > + addi sp, sp, -RISCV_SZPTR
> > > > > + REG_S fp, (sp)
> > > > > +
> > > > > + /* Save sp in fp */
> > > > > + move fp, sp
> > > > > +
> > > > > + /* Move to the new stack and call the function there */
> > > > > + li a3, IRQ_STACK_SIZE
> > > > > + add sp, a1, a3
> > > > > + jalr a2
> > > > > +
> > > > > + /*
> > > > > + * Restore sp from prev fp, and fp, ra from the frame
> > > > > + */
> > > > > + move sp, fp
> > > > > + REG_L fp, (sp)
> > > > > + addi sp, sp, RISCV_SZPTR
> > > > > + REG_L ra, (sp)
> > > > > + addi sp, sp, RISCV_SZPTR
> > > > > + ret
> > > > > +ENDPROC(call_on_stack)
> > > >
> > > > IIRC x86_64 moved away from a stack-switch function like this because it
> > > > presents a convenient exploit gadget.
> > > I found:
> > > https://lore.kernel.org/all/20210204204903.350275743@linutronix.de/
> > >
> > > - The fact that the stack switching code ended up being an easy to find
> > > exploit gadget.
> > >
> > > What's the exploit gadget? Do you have a ref link? Thx.
> >
> > Sadly no, I do not. Kees might. But basically it boils down to this
> > function taking both a stack pointer and a function pointer as
> > arguments (@a1 and @a2 resp. if I'm not reading this wrong).
> >
> > If an attacker can call this with arguments of its choice then it gains
> > full control of subsequent execution.
>
> If you inline it the hope is that the function pointers go away or at
> least the encompassing function doesn't have quite such a 'convenient'
> signature to hijack control flow.
Thanks for mentioning it. I would change to an inline style.
--
Best Regards
Guo Ren
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next prev parent reply other threads:[~2022-09-21 6:16 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-18 15:52 [PATCH V5 00/11] riscv: Add GENERIC_ENTRY support and related features guoren
2022-09-18 15:52 ` [PATCH V5 01/11] riscv: elf_kexec: Fixup compile warning guoren
2022-09-18 15:52 ` [PATCH V5 02/11] riscv: compat_syscall_table: " guoren
2022-09-18 15:52 ` [PATCH V5 03/11] riscv: ptrace: Remove duplicate operation guoren
2022-09-18 15:52 ` [PATCH V5 04/11] compiler_types.h: Add __noinstr_section() for noinstr guoren
2022-09-18 15:52 ` [PATCH V5 05/11] riscv: traps: Add noinstr to prevent instrumentation inserted guoren
2022-09-18 15:52 ` [PATCH V5 06/11] entry: Prevent DEBUG_PREEMPT warning guoren
2022-09-19 11:58 ` Peter Zijlstra
2022-09-20 1:45 ` Guo Ren
2022-09-30 12:27 ` Guo Ren
2022-09-18 15:52 ` [PATCH V5 07/11] riscv: convert to generic entry guoren
2022-09-19 13:34 ` Peter Zijlstra
2022-09-20 6:36 ` Guo Ren
2022-09-20 7:22 ` Peter Zijlstra
2022-09-30 11:28 ` Guo Ren
2022-09-18 15:52 ` [PATCH V5 08/11] riscv: Support HAVE_IRQ_EXIT_ON_IRQ_STACK guoren
2022-09-19 13:45 ` Peter Zijlstra
2022-09-20 6:08 ` Guo Ren
2022-09-20 7:27 ` Peter Zijlstra
2022-09-20 7:34 ` Peter Zijlstra
2022-09-21 6:16 ` Guo Ren [this message]
2022-09-21 8:34 ` Chen Zhongjin
2022-09-21 9:53 ` Guo Ren
2022-09-21 11:56 ` Chen Zhongjin
2022-09-22 1:26 ` Guo Ren
2022-09-18 15:52 ` [PATCH V5 09/11] riscv: Support HAVE_SOFTIRQ_ON_OWN_STACK guoren
2022-09-20 0:11 ` Guo Ren
2022-09-18 15:52 ` [PATCH V5 10/11] riscv: Add config of thread stack size guoren
2022-09-18 15:52 ` [PATCH V5 11/11] riscv: Add support for STACKLEAK gcc plugin guoren
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