From: Denys Vlasenko <dvlasenk@redhat.com>
To: Borislav Petkov <bp@alien8.de>
Cc: "Andy Lutomirski" <luto@amacapital.net>,
"Brian Gerst" <brgerst@gmail.com>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Oleg Nesterov" <oleg@redhat.com>,
"Ingo Molnar" <mingo@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Andy Lutomirski" <luto@kernel.org>,
"Will Drewry" <wad@chromium.org>,
"Frédéric Weisbecker" <fweisbec@gmail.com>,
"Alexei Starovoitov" <ast@plumgrid.com>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Kees Cook" <keescook@chromium.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
"linux-tip-commits@vger.kernel.org"
<linux-tip-commits@vger.kernel.org>
Subject: Re: [tip:x86/vdso] x86/vdso32/syscall.S: Do not load __USER32_DS to %ss
Date: Thu, 23 Apr 2015 12:26:43 +0200 [thread overview]
Message-ID: <5538C8E3.60009@redhat.com> (raw)
In-Reply-To: <20150423101840.GC28327@pd.tnic>
On 04/23/2015 12:18 PM, Borislav Petkov wrote:
> On Thu, Apr 23, 2015 at 11:56:21AM +0200, Denys Vlasenko wrote:
>> The fix can look like this (untested):
>>
>>
>> diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
>> index 0c302d0..9f4c232 100644
>> --- a/arch/x86/ia32/ia32entry.S
>> +++ b/arch/x86/ia32/ia32entry.S
>> @@ -198,6 +198,18 @@ sysexit_from_sys_call:
>> * with 'sysenter' and it uses the SYSENTER calling convention.
>> */
>> andl $~TS_COMPAT,ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)
>> + /*
>> + * On AMD, SYSRET32 does not modify %ss cached descriptor;
>
> Ok, but doc says that in both long and compat mode, SYSRET does load
> SS.sel with the value in MSR_STAR...
Yes. It loads *selector*. AMD docs say that selector is loaded as you say,
but *cached descriptor* of SS (which is a different entity) is not modified.
If *cached descriptor* is invalid, in 32-bit mode stack ops
will fail. (In 64-bit mode, CPU doesn't do those checks).
next prev parent reply other threads:[~2015-04-23 10:27 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-26 1:11 [GIT PULL] x86/vdso changes for 4.1 Andy Lutomirski
[not found] ` <efe1ec29eda830b1d0030882706f3dac99ce1f73.1427482063.git.luto@kernel.org>
2015-03-27 18:47 ` [GIT PULL 2/4] x86: vdso32/syscall.S: do not load __USER32_DS to %ss Andy Lutomirski
2015-03-27 18:48 ` [GIT PULL 1/4] x86,vdso: fix the x86 vdso2c tool includes Andy Lutomirski
2015-03-27 18:48 ` [GIT PULL 2/4] x86: vdso32/syscall.S: do not load __USER32_DS to %ss Andy Lutomirski
2015-03-31 12:38 ` [tip:x86/vdso] x86/vdso32/syscall.S: Do " tip-bot for Denys Vlasenko
2015-04-23 7:37 ` Brian Gerst
2015-04-23 8:49 ` Andy Lutomirski
2015-04-23 9:07 ` Andy Lutomirski
2015-04-23 9:23 ` Denys Vlasenko
2015-04-23 9:47 ` Borislav Petkov
2015-04-23 9:56 ` Denys Vlasenko
2015-04-23 10:18 ` Borislav Petkov
2015-04-23 10:26 ` Denys Vlasenko [this message]
2015-04-23 10:44 ` Borislav Petkov
2015-04-23 11:05 ` Denys Vlasenko
2015-04-23 15:48 ` Andy Lutomirski
2015-04-23 16:41 ` Denys Vlasenko
2015-04-23 16:50 ` Andy Lutomirski
2015-04-23 17:14 ` Borislav Petkov
2015-04-23 18:24 ` Andy Lutomirski
2015-04-23 18:36 ` Linus Torvalds
2015-04-23 18:52 ` Borislav Petkov
2015-04-23 19:20 ` Andy Lutomirski
2015-04-23 19:50 ` Denys Vlasenko
2015-04-23 9:20 ` Denys Vlasenko
2015-04-23 9:56 ` Borislav Petkov
2015-04-23 11:11 ` Brian Gerst
2015-04-23 11:28 ` Brian Gerst
2015-04-23 11:46 ` Denys Vlasenko
2015-04-23 12:01 ` Brian Gerst
2015-04-23 12:35 ` Denys Vlasenko
2015-04-23 11:12 ` Denys Vlasenko
2015-03-27 18:48 ` [GIT PULL 3/4] x86, vdso: teach 'make clean' remove generated vdso-image-*.c files Andy Lutomirski
2015-03-31 12:38 ` [tip:x86/vdso] x86/vdso: Teach 'make clean' to " tip-bot for Andrey Skvortsov
2015-03-27 18:48 ` [GIT PULL 4/4] x86, vdso: Remove x32 intermediates during 'make clean' Andy Lutomirski
2015-03-31 12:39 ` [tip:x86/vdso] x86/vdso: Remove x32 intermediates during ' make clean' tip-bot for Andy Lutomirski
2015-03-31 12:38 ` [tip:x86/vdso] x86/vdso: Fix the x86 vdso2c tool includes tip-bot for Tommi Kyntola
-- strict thread matches above, loose matches on Subject: below --
2015-02-16 14:15 [PATCH] x86,vdso: fix " Tommi Kyntola
2015-02-16 16:29 ` Andy Lutomirski
[not found] ` <CAO2cUkRstHcKzy+sMvaQoXHBjTX1yheN2EMQW-wCd0tDRCLNYQ@mail.gmail.com>
2015-02-16 20:40 ` Andy Lutomirski
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