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Date:   Thu, 4 Mar 2021 00:44:08 +0300
From:   "Dmitry V. Levin" <ldv@altlinux.org>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Sergei Trofimovich <slyfox@gentoo.org>,
        linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org
Subject: Re: [PATCH] ia64: fix ptrace(PTRACE_SYSCALL_INFO_EXIT) sign
Message-ID: <20210303214408.GB19445@altlinux.org>
References: <20210221002554.333076-1-slyfox@gentoo.org>
 <20210221002554.333076-2-slyfox@gentoo.org>
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In-Reply-To: <20210221002554.333076-2-slyfox@gentoo.org>
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On Sun, Feb 21, 2021 at 12:25:54AM +0000, Sergei Trofimovich wrote:
> In https://bugs.gentoo.org/769614 Dmitry noticed that
> `ptrace(PTRACE_GET_SYSCALL_INFO)` does not return error sign properly.
> 
> The bug is in mismatch between get/set errors:
> 
> static inline long syscall_get_error(struct task_struct *task,
>                                      struct pt_regs *regs)
> {
>         return regs->r10 == -1 ? regs->r8:0;
> }
> 
> static inline long syscall_get_return_value(struct task_struct *task,
>                                             struct pt_regs *regs)
> {
>         return regs->r8;
> }
> 
> static inline void syscall_set_return_value(struct task_struct *task,
>                                             struct pt_regs *regs,
>                                             int error, long val)
> {
>         if (error) {
>                 /* error < 0, but ia64 uses > 0 return value */
>                 regs->r8 = -error;
>                 regs->r10 = -1;
>         } else {
>                 regs->r8 = val;
>                 regs->r10 = 0;
>         }
> }
> 
> Tested on v5.10 on rx3600 machine (ia64 9040 CPU).
> 
> CC: linux-ia64@vger.kernel.org
> CC: linux-kernel@vger.kernel.org
> CC: Andrew Morton <akpm@linux-foundation.org>
> Reported-by: Dmitry V. Levin <ldv@altlinux.org>
> Bug: https://bugs.gentoo.org/769614
> Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
> ---
>  arch/ia64/include/asm/syscall.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/ia64/include/asm/syscall.h b/arch/ia64/include/asm/syscall.h
> index 6c6f16e409a8..0d23c0049301 100644
> --- a/arch/ia64/include/asm/syscall.h
> +++ b/arch/ia64/include/asm/syscall.h
> @@ -32,7 +32,7 @@ static inline void syscall_rollback(struct task_struct *task,
>  static inline long syscall_get_error(struct task_struct *task,
>  				     struct pt_regs *regs)
>  {
> -	return regs->r10 == -1 ? regs->r8:0;
> +	return regs->r10 == -1 ? -regs->r8:0;
>  }
>  
>  static inline long syscall_get_return_value(struct task_struct *task,

Reviewed-by: Dmitry V. Levin <ldv@altlinux.org>


-- 
ldv