Re: [PATCH] riscv: reject invalid syscalls below -1

Andreas Schwab
2019-12-18T10:35:30Z

On Dez 18 2019, David Abdurachmanov wrote:

> 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.

So check for -1 first, then for out-of-range?

Andreas.

--
Andreas Schwab, SUSE Labs, schwab@suse.de
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