x86/fpu: Fix invalid FPU ptrace state after execve()
authorYu-cheng Yu <yu-cheng.yu@intel.com>
Thu, 17 Nov 2016 17:11:35 +0000 (09:11 -0800)
committerIngo Molnar <mingo@kernel.org>
Mon, 21 Nov 2016 09:38:35 +0000 (10:38 +0100)
commitb22cbe404a9cc3c7949e380fa1861e31934c8978
treeb88f02a3b34c3d138a96b9f6174ab66e643c3af0
parented68d7e9b9cfb64f3045ffbcb108df03c09a0f98
x86/fpu: Fix invalid FPU ptrace state after execve()

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 fpu__clear() does not properly clear fpstate.
Fix it by doing just that.

Reported-by: Robert O'Callahan <robert@ocallahan.org>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: <stable@vger.kernel.org>
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: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi V. Shankar <ravi.v.shankar@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1479402695-6553-1-git-send-email-yu-cheng.yu@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/kernel/fpu/core.c