forked from AUR/linux-vfio
66 lines
2.1 KiB
Diff
66 lines
2.1 KiB
Diff
From 885bad1e5f32bbf30787ead9578f8174047e6904 Mon Sep 17 00:00:00 2001
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From: Yu-cheng Yu <yu-cheng.yu@intel.com>
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Date: Thu, 17 Nov 2016 09:11:35 -0800
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Subject: [PATCH] x86/fpu: Fix invalid FPU ptrace state after execve()
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commit b22cbe404a9cc3c7949e380fa1861e31934c8978 upstream.
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Robert O'Callahan reported that after an execve PTRACE_GETREGSET
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NT_X86_XSTATE continues to return the pre-exec register values
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until the exec'ed task modifies FPU state.
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The test code is at:
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https://bugzilla.redhat.com/attachment.cgi?id=1164286.
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What is happening is fpu__clear() does not properly clear fpstate.
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Fix it by doing just that.
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Reported-by: Robert O'Callahan <robert@ocallahan.org>
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Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
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Cc: Andy Lutomirski <luto@kernel.org>
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Cc: Borislav Petkov <bp@suse.de>
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Cc: David Hansen <dave.hansen@linux.intel.com>
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Cc: Fenghua Yu <fenghua.yu@intel.com>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Cc: Ravi V. Shankar <ravi.v.shankar@intel.com>
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Cc: Thomas Gleixner <tglx@linutronix.de>
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Link: http://lkml.kernel.org/r/1479402695-6553-1-git-send-email-yu-cheng.yu@intel.com
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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arch/x86/kernel/fpu/core.c | 16 ++++++++--------
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1 file changed, 8 insertions(+), 8 deletions(-)
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diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
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index 3fc03a09a93b1710..c289e2f4a6e5b464 100644
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--- a/arch/x86/kernel/fpu/core.c
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+++ b/arch/x86/kernel/fpu/core.c
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@@ -517,14 +517,14 @@ void fpu__clear(struct fpu *fpu)
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{
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WARN_ON_FPU(fpu != ¤t->thread.fpu); /* Almost certainly an anomaly */
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- if (!use_eager_fpu() || !static_cpu_has(X86_FEATURE_FPU)) {
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- /* FPU state will be reallocated lazily at the first use. */
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- fpu__drop(fpu);
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- } else {
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- if (!fpu->fpstate_active) {
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- fpu__activate_curr(fpu);
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- user_fpu_begin();
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- }
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+ fpu__drop(fpu);
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+
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+ /*
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+ * Make sure fpstate is cleared and initialized.
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+ */
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+ if (static_cpu_has(X86_FEATURE_FPU)) {
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+ fpu__activate_curr(fpu);
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+ user_fpu_begin();
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copy_init_fpstate_to_fpregs();
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}
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}
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--
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2.10.2
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