linux-kernel - Re: [PATCH] x86/asm/entry/32: Reinstate clearing of pt

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Message-ID: <20150608065003.GA28899@gmail.com>
Date:	Mon, 8 Jun 2015 08:50:03 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Denys Vlasenko <dvlasenk@...hat.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andy Lutomirski <luto@...capital.net>,
	Oleg Nesterov <oleg@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Alexei Starovoitov <ast@...mgrid.com>,
	Will Drewry <wad@...omium.org>,
	Kees Cook <keescook@...omium.org>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/asm/entry/32: Reinstate clearing of pt_regs->r8..r11
 on EFAULT path


* Denys Vlasenko <dvlasenk@...hat.com> wrote:

> I broke this recently when I changed pt_regs->r8..r11 clearing logic
> in INT 80 code path.
> 
> There is a branch from SYSENTER/SYSCALL code to INT 80 code:
> if we fail to retrieve arg6, we return EFAULT. Before this patch,
> in this case we don't clear pt_regs->r8..r11.
> 
> This patch fixes this. The resulting code is smaller and simpler.

So how did you notice this bug - through actual info leak testing, or review?

Thanks,

	Ingo
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