Message-ID: <557590DC.8050703@redhat.com>
Date: Mon, 08 Jun 2015 14:55:56 +0200
From: Denys Vlasenko <dvlasenk@redhat.com>
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To: Ingo Molnar <mingo@kernel.org>
CC: Linus Torvalds <torvalds@linux-foundation.org>,
        Steven Rostedt <rostedt@goodmis.org>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Andy Lutomirski <luto@amacapital.net>, Oleg Nesterov <oleg@redhat.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Alexei Starovoitov <ast@plumgrid.com>, Will Drewry <wad@chromium.org>,
        Kees Cook <keescook@chromium.org>, x86@kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/asm/entry/32: Reinstate clearing of pt_regs->r8..r11
 on EFAULT path
References: <1433701470-28800-1-git-send-email-dvlasenk@redhat.com> <20150608065003.GA28899@gmail.com>
In-Reply-To: <20150608065003.GA28899@gmail.com>
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On 06/08/2015 08:50 AM, Ingo Molnar wrote:
> * Denys Vlasenko <dvlasenk@redhat.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?

By reviewing my own patch.
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