Messages in this thread Patch in this message | | | From | Yu-cheng Yu <> | Subject | [PATCH] x86/fpu: Fix invalid FPU ptrace state after execve | Date | Wed, 16 Nov 2016 08:56:36 -0800 |
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Robert O'Callahan reported that after an execve PTRACE_GETREGSET NT_X86_XSTATE continues to return the pre-exec register values until the exec'ed task modifies FPU state. The test code is at https://bugzilla.redhat.com/attachment.cgi?id=1164286.
What is happening is when eagerfpu is enabled, fpu__clear() did not properly clear fpstate. Fix it by doing just that.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> Reported-by: Robert O'Callahan <robert@ocallahan.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@suse.de> Cc: David Hansen <dave.hansen@linux.intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> --- arch/x86/kernel/fpu/core.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 4700401..4c203c4 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -521,14 +521,14 @@ void fpu__clear(struct fpu *fpu) { WARN_ON_FPU(fpu != ¤t->thread.fpu); /* Almost certainly an anomaly */ - if (!use_eager_fpu() || !static_cpu_has(X86_FEATURE_FPU)) { - /* FPU state will be reallocated lazily at the first use. */ - fpu__drop(fpu); - } else { - if (!fpu->fpstate_active) { - fpu__activate_curr(fpu); - user_fpu_begin(); - } + fpu__drop(fpu); + + /* + * When eagerfpu is used, make sure fpstate is cleared and initialized. + */ + if (use_eager_fpu()) { + fpu__activate_curr(fpu); + user_fpu_begin(); copy_init_fpstate_to_fpregs(); } } -- 1.9.1
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