linux-kernel - Re: [PATCH 04/20] x86: Rewrite copy_siginfo_{to,from}

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Message-ID: <20151015184158.GA30643@redhat.com>
Date:	Thu, 15 Oct 2015 20:41:58 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	"Amanieu d'Antras" <amanieu@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>, x86@...nel.org,
	Brian Gerst <brgerst@...il.com>
Subject: Re: [PATCH 04/20] x86: Rewrite copy_siginfo_{to,from}_user32

OOH ;) I'll try to look at this patch and the changes in the generic
code later. A couple of nits right now.

Please CC x86 maintainers, not only x86@...nel.org.

Please do not remove get/put_user_ex from this code. And this reminds
me that we can improve *user_try/*user_catch ...

On 10/14, Amanieu d'Antras wrote:
>
> -int copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from)
> +int copy_siginfo_to_user32(struct compat_siginfo __user *to, const siginfo_t *from)
>  {
> -	int err = 0;
> +	int err, si_code;
>  	bool ia32 = test_thread_flag(TIF_IA32);
>  
> -	if (!access_ok(VERIFY_WRITE, to, sizeof(compat_siginfo_t)))
> +	if (!access_ok(VERIFY_WRITE, to, sizeof(siginfo_t)))

Why? This looks wrong.

> +	if (from->si_code < 0) {
> +		err |= __copy_to_user(to->_sifields._pad, from->_sifields._pad, SI_PAD_SIZE * sizeof(int))
> +			? -EFAULT : 0;
> +		return err;

I think you should split this patch. And this change (don't interpet,
just copy) should go as a separate change.

> +	switch (from->si_code & __SI_MASK) {
> +	case __SI_KILL:

I agree, this looks better than ">> 16", but I'd suggest a separate
change too.

[...snip...]

the rest looks unreviewable because you didn't split it and because
you removed try/catch ;) The same for copy-from-user.

Please help us to understand these changes and make the more reviewable
patches if possible. Personally I think you have a point.

Oleg.

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