From: Guo Ren <guoren@kernel.org>
To: Ben Hutchings <ben@decadent.org.uk>
Cc: arnd@arndb.de, palmer@rivosinc.com, tglx@linutronix.de,
peterz@infradead.org, 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,
chenzhongjin@huawei.com, greentime.hu@sifive.com,
andy.chiu@sifive.com, linux-arch@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org,
Guo Ren <guoren@linux.alibaba.com>
Subject: Re: [PATCH -next V8 06/14] riscv: convert to generic entry
Date: Mon, 28 Nov 2022 10:42:44 +0800 [thread overview]
Message-ID: <CAJF2gTQwkPgafMxJ8YxH-kCsyT82bTr_a2hBJ1Pido7SvN+o2A@mail.gmail.com> (raw)
In-Reply-To: <a28d32c965f363ce099bd0a65e1c82b75a98128a.camel@decadent.org.uk>
On Mon, Nov 28, 2022 at 12:26 AM Ben Hutchings <ben@decadent.org.uk> wrote:
>
> On Thu, 2022-11-03 at 03:50 -0400, guoren@kernel.org wrote:
> [...]
> > --- a/arch/riscv/kernel/sys_riscv.c
> > +++ b/arch/riscv/kernel/sys_riscv.c
> [...]
> > +asmlinkage void do_sys_ecall_u(struct pt_regs *regs)
> > +{
> > + syscall_t syscall;
> > + ulong nr = regs->a7;
> > +
> > + regs->epc += 4;
> > + regs->orig_a0 = regs->a0;
> > + regs->a0 = -ENOSYS;
> > +
> > + nr = syscall_enter_from_user_mode(regs, nr);
> > +#ifdef CONFIG_COMPAT
> > + if ((regs->status & SR_UXL) == SR_UXL_32)
> > + syscall = compat_sys_call_table[nr];
> > + else
> > +#endif
> > + syscall = sys_call_table[nr];
> > +
> > + if (nr < NR_syscalls)
>
> This bounds check needs to be done before indexing the system call
> table, not after.
Yes, you are right. That would cause a wrong pointer bug. Here is the
new version:
asmlinkage void do_sys_ecall_u(struct pt_regs *regs)
{
syscall_t syscall;
ulong nr = regs->a7;
regs->epc += 4;
regs->orig_a0 = regs->a0;
regs->a0 = -ENOSYS;
nr = syscall_enter_from_user_mode(regs, nr);
if (nr < NR_syscalls) {
#ifdef CONFIG_COMPAT
if ((regs->status & SR_UXL) == SR_UXL_32)
syscall = compat_sys_call_table[nr];
else
#endif
syscall = sys_call_table[nr];
regs->a0 = syscall(regs->orig_a0, regs->a1, regs->a2,
regs->a3, regs->a4, regs->a5, regs->a6);
}
syscall_exit_to_user_mode(regs);
}
>
> Ben.
>
> > + regs->a0 = syscall(regs->orig_a0, regs->a1, regs->a2,
> > + regs->a3, regs->a4, regs->a5, regs->a6);
> > + syscall_exit_to_user_mode(regs);
> > +}
> [...]
>
> --
> Ben Hutchings
> This sentence contradicts itself - no actually it doesn't.
--
Best Regards
Guo Ren
_______________________________________________
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linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2022-11-28 2:43 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-03 7:50 [PATCH -next V8 00/14] riscv: Add GENERIC_ENTRY support and related features guoren
2022-11-03 7:50 ` [PATCH -next V8 01/14] compiler_types.h: Add __noinstr_section() for noinstr guoren
2022-12-05 9:12 ` Björn Töpel
2022-11-03 7:50 ` [PATCH -next V8 02/14] riscv: elf_kexec: Fixup compile warning guoren
2022-12-05 9:13 ` Björn Töpel
2022-12-06 4:39 ` Guo Ren
2022-11-03 7:50 ` [PATCH -next V8 03/14] riscv: compat_syscall_table: " guoren
2022-12-05 9:13 ` Björn Töpel
2022-11-03 7:50 ` [PATCH -next V8 04/14] riscv: ptrace: Remove duplicate operation guoren
2022-12-05 9:34 ` Björn Töpel
2022-12-06 4:41 ` Guo Ren
2022-11-03 7:50 ` [PATCH -next V8 05/14] riscv: traps: Add noinstr to prevent instrumentation inserted guoren
2022-11-03 7:50 ` [PATCH -next V8 06/14] riscv: convert to generic entry guoren
2022-11-27 16:25 ` Ben Hutchings
2022-11-28 2:42 ` Guo Ren [this message]
2022-12-05 10:49 ` Björn Töpel
2022-12-06 6:39 ` Guo Ren
2022-11-03 7:50 ` [PATCH -next V8 07/14] riscv: Support HAVE_IRQ_EXIT_ON_IRQ_STACK guoren
2022-11-03 7:50 ` [PATCH -next V8 08/14] riscv: Support HAVE_SOFTIRQ_ON_OWN_STACK guoren
2022-11-03 7:50 ` [PATCH -next V8 09/14] riscv: Add config of thread stack size guoren
2022-11-03 7:50 ` [PATCH -next V8 10/14] riscv: Typo fixup for addi -> andi in comment guoren
2022-12-05 9:18 ` Björn Töpel
2022-11-03 7:50 ` [PATCH -next V8 11/14] riscv: Add support for STACKLEAK gcc plugin guoren
2022-11-03 7:50 ` [PATCH -next V8 12/14] riscv: remove extra level wrappers of trace_hardirqs_{on,off} guoren
2022-11-03 7:50 ` [PATCH -next V8 13/14] riscv: consolidate ret_from_kernel_thread into ret_from_fork guoren
2022-11-03 7:50 ` [PATCH -next V8 14/14] riscv: entry: consolidate general regs saving/restoring guoren
2022-11-23 15:26 ` [PATCH -next V8 00/14] riscv: Add GENERIC_ENTRY support and related features Jisheng Zhang
2022-12-05 9:46 ` Björn Töpel
2022-12-06 6:12 ` Guo Ren
2022-12-06 7:03 ` Björn Töpel
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