From: Ingo Molnar <mingo@kernel.org>
To: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>,
security@kernel.org, x86@kernel.org,
linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Rudolf Marek <r.marek@assembler.cz>,
Denys Vlasenko <dvlasenk@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v3 2/7] x86/arch_prctl: Fix ARCH_GET_FS and ARCH_GET_GS
Date: Fri, 8 Apr 2016 09:13:54 +0200 [thread overview]
Message-ID: <20160408071354.GB22579@gmail.com> (raw)
In-Reply-To: <c6e7b507c72ca3bdbf6c7a8a3ceaa0334e873bd9.1460075211.git.luto@kernel.org>
* Andy Lutomirski <luto@kernel.org> wrote:
> ARCH_GET_FS and ARCH_GET_GS attempted to figure out the fsbase and
> gsbase respectively from saved thread state. This was wrong: fsbase
> and gsbase live in registers while a thread is running, not in
> memory.
So I'm wondering, the current code looks totally broken,what user-space code can
possibly use this? I checked glibc and Wine, and neither of them does. Wine uses
ARCH_SET_GS and glibc uses ARCH_SET_FS, but that's all - neither actually tries to
use the ARCH_GET_* reading APIs.
So for backporting purposes I'd be much happier about simply returning -EINVAL or
-ENOSYS, and we could re-introduce this code in v4.7.
Thanks,
Ingo
next prev parent reply other threads:[~2016-04-08 7:14 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-08 0:31 [PATCH v3 0/7] x86: Pile o' FS/GS changes Andy Lutomirski
2016-04-08 0:31 ` [PATCH v3 1/7] selftests/x86: Test the FSBASE/GSBASE API and context switching Andy Lutomirski
2016-04-13 11:28 ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-04-08 0:31 ` [PATCH v3 5/7] x86/cpu: Move X86_BUG_ESPFIX initialization to generic_identify Andy Lutomirski
2016-04-13 11:30 ` [tip:x86/asm] x86/cpu: Move X86_BUG_ESPFIX initialization to generic_identify() tip-bot for Andy Lutomirski
2016-04-08 0:31 ` [PATCH v3 7/7] x86/entry: Make gs_change a local label Andy Lutomirski
2016-04-13 11:31 ` [tip:x86/asm] x86/entry/64: " tip-bot for Borislav Petkov
2016-04-08 10:39 ` [PATCH v3 0/7] x86: Pile o' FS/GS changes Borislav Petkov
2016-04-08 10:40 ` Borislav Petkov
[not found] ` <c6e7b507c72ca3bdbf6c7a8a3ceaa0334e873bd9.1460075211.git.luto@kernel.org>
2016-04-08 7:13 ` Ingo Molnar [this message]
2016-04-08 9:39 ` [PATCH v3 2/7] x86/arch_prctl: Fix ARCH_GET_FS and ARCH_GET_GS Dmitry Safonov
2016-04-08 16:03 ` Andy Lutomirski
2016-04-13 11:29 ` [tip:x86/asm] " tip-bot for Andy Lutomirski
[not found] ` <aec6b2df1bfc56101d4e9e2e5d5d570bf41663c6.1460075211.git.luto@kernel.org>
2016-04-08 1:40 ` [PATCH v3 6/7] x86/cpu: Add Erratum 88 detection on AMD Andy Lutomirski
2016-04-08 9:51 ` Borislav Petkov
2016-04-13 11:30 ` [tip:x86/asm] " tip-bot for Borislav Petkov
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