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From:   damian <damian.tometzki@familie-tometzki.de>
Date:   Tue, 27 Oct 2020 20:19:20 +0100
To:     Jens Axboe <axboe@kernel.dk>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Christoph Hellwig <hch@lst.de>, Kyle Huey <me@kylehuey.com>
Subject: Re: [PATCH] Fix compat regression in process_vm_rw()
Message-ID: <20201027191920.GA262123@centos.familie-tometzki.de>
Mail-Followup-To: Jens Axboe <axboe@kernel.dk>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Christoph Hellwig <hch@lst.de>, Kyle Huey <me@kylehuey.com>
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On Mo, 26. Okt 18:03, Jens Axboe wrote:
> The removal of compat_process_vm_{readv,writev} didn't change
> process_vm_rw(), which always assumes it's not doing a compat syscall.
> Instead of passing in 'false' unconditionally for 'compat', make it
> conditional on in_compat_syscall().
> 
> Fixes: c3973b401ef2 ("mm: remove compat_process_vm_{readv,writev}")
> Reported-by: Kyle Huey <me@kylehuey.com>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> 
> ---
> 
> diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
> index fd12da80b6f2..05676722d9cd 100644
> --- a/mm/process_vm_access.c
> +++ b/mm/process_vm_access.c
> @@ -273,7 +273,8 @@ static ssize_t process_vm_rw(pid_t pid,
>  		return rc;
>  	if (!iov_iter_count(&iter))
>  		goto free_iov_l;
> -	iov_r = iovec_from_user(rvec, riovcnt, UIO_FASTIOV, iovstack_r, false);
> +	iov_r = iovec_from_user(rvec, riovcnt, UIO_FASTIOV, iovstack_r,
> +				in_compat_syscall());
>  	if (IS_ERR(iov_r)) {
>  		rc = PTR_ERR(iov_r);
>  		goto free_iov_l;
> 
> -- 
> Jens Axboe
> 
Hello Jens,

i got the following error when i try to build. 

m/process_vm_access.c: In Funktion ?process_vm_rw?:
mm/process_vm_access.c:277:5: Fehler: Implizite Deklaration der Funktion ?in_compat_syscall?; meinten Sie ?in_ia32_syscall?? [-Werror=implicit-function-declaration]
  277 |     in_compat_syscall());
      |     ^~~~~~~~~~~~~~~~~
      |     in_ia32_syscall

-- 
VG
Damian Tometzki