linux-kernel - Re: [PATCH] riscv: entry: always initialize regs->a0 to -ENOSYS

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Date: Thu, 27 Jun 2024 22:29:00 +0800
From: Celeste Liu <coelacanthushex@...il.com>
To: Björn Töpel <bjorn@...nel.org>,
 linux-riscv@...ts.infradead.org, Björn Töpel
 <bjorn@...osinc.com>, "Dmitry V . Levin" <ldv@...ace.io>
Cc: linux-kernel@...r.kernel.org, Guo Ren <guoren@...nel.org>,
 Palmer Dabbelt <palmer@...osinc.com>,
 Emil Renner Berthing <emil.renner.berthing@...onical.com>,
 Felix Yan <felixonmars@...hlinux.org>, Ruizhe Pan <c141028@...il.com>,
 stable@...r.kernel.org
Subject: Re: [PATCH] riscv: entry: always initialize regs->a0 to -ENOSYS

On 2024-06-27 22:08, Björn Töpel wrote:

> Celeste Liu <coelacanthushex@...il.com> writes:
> 
>> Otherwise when the tracer changes syscall number to -1, the kernel fails
>> to initialize a0 with -ENOSYS and subsequently fails to return the error
>> code of the failed syscall to userspace. For example, it will break
>> strace syscall tampering.
>>
>> Fixes: 52449c17bdd1 ("riscv: entry: set a0 = -ENOSYS only when syscall != -1")
>> Cc: stable@...r.kernel.org
>> Signed-off-by: Celeste Liu <CoelacanthusHex@...il.com>
> 
> Reported-by: "Dmitry V. Levin" <ldv@...ace.io>
> Reviewed-by: Björn Töpel <bjorn@...osinc.com>

Patch v2 has been sent.